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From: Jon Watte <jwatte@gm...>  20090529 16:01:27

Ron Hay wrote: > stated, pretty much all they have been doing. We want to do it better, > so I was try to edumacate myself on some other possibilities using > "modern" (aka "not 10 years old") hardware. Some of the ideas you > through out are a good start Jon :) > The "colorful" IR is simply a palette map at the end of the shader. Once you have "intensity" then you map that to the S texture coordinate of a color ramp texture, and out comes the display color. Depending on which piece of hardware you want to emulate, typically you apply bloom BEFORE the palettization, which means you need some render target pingponging. Sincerely, jw 
From: Ron Hay <rhay@cy...>  20090528 20:15:40

Thanks for the response  to answer some questions, it's the "colorful" variant of IR that's probably going to be emulated. They additionally want night vision (which is an easier effect, in general). I'm looking for a bit more than a different set of textures, which is, as Jon stated, pretty much all they have been doing. We want to do it better, so I was try to edumacate myself on some other possibilities using "modern" (aka "not 10 years old") hardware. Some of the ideas you through out are a good start Jon :) Ron Jon Watte wrote: > Ron Hay wrote: > >> Anyone have points to papers/tutorials/explanations of some algorithms >> for rendering a scene as it would appear through a thermal IR camera? >> As in military operations stuff. Anything ranging from "good enough" to >> a decent approximation of reality is usable. >> >> > > What the military guys do is generally build a second set of textures > for everything, where the texture values correspond to frequencies in > the IR spectrum instead of the visible RGB spectrum. Additionally, as > this is usually done for night vision, you render without lighting, but > instead using fullbright (or some variation thereof) textures. The > reason for this is that materials typically have very different behavior > in the IR spectrum than in the visible spectrum  a lawn, a garden > hose, and a painted metal grate can all be "green," but they behave > really differently in IR. > Depending on what kind of simulation you're doing, you might want to use > a texture channel or two for parameters such as "decay," such that you > can pass in a parameter like "time since last exposure to sunlight" and > get a better emulation of how a scene will change over time  different > materials cool differently. > Finally, if you want to emulate the "look" of a particular IR sensor or > display, you should get a copy of the real thing, or barring that, some > video of the real thing, and add whatever artifacts you can see > (striping, bright bands, knockout, ringing, etc) as shader effects, > until it's close enough. > > Sincerely, > > jw > >  > Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT > is a gathering of techside developers & brand creativity professionals. Meet > the minds behind Google Creative Lab, Visual Complexity, Processing, & > iPhoneDevCamp as they present alongside digital heavyweights like Barbarian > Group, R/GA, & Big Spaceship. http://p.sf.net/sfu/creativitycatcom > _______________________________________________ > GDAlgorithmslist mailing list > GDAlgorithmslist@... > https://lists.sourceforge.net/lists/listinfo/gdalgorithmslist > Archives: > http://sourceforge.net/mailarchive/forum.php?forum_name=gdalgorithmslist > 
From: Jon Watte <jwatte@gm...>  20090528 19:16:52

Ron Hay wrote: > Anyone have points to papers/tutorials/explanations of some algorithms > for rendering a scene as it would appear through a thermal IR camera? > As in military operations stuff. Anything ranging from "good enough" to > a decent approximation of reality is usable. > What the military guys do is generally build a second set of textures for everything, where the texture values correspond to frequencies in the IR spectrum instead of the visible RGB spectrum. Additionally, as this is usually done for night vision, you render without lighting, but instead using fullbright (or some variation thereof) textures. The reason for this is that materials typically have very different behavior in the IR spectrum than in the visible spectrum  a lawn, a garden hose, and a painted metal grate can all be "green," but they behave really differently in IR. Depending on what kind of simulation you're doing, you might want to use a texture channel or two for parameters such as "decay," such that you can pass in a parameter like "time since last exposure to sunlight" and get a better emulation of how a scene will change over time  different materials cool differently. Finally, if you want to emulate the "look" of a particular IR sensor or display, you should get a copy of the real thing, or barring that, some video of the real thing, and add whatever artifacts you can see (striping, bright bands, knockout, ringing, etc) as shader effects, until it's close enough. Sincerely, jw 
From: <logout@fr...>  20090528 15:10:46

Hello, can't you just use grayscale textures that represent body heat + some fancy pixel shader to get the result you want ? It should be decent enough to be acceptable (but will require you to use another set of textures). If you want to get some reference images, I believe that some Sony camera and recorders have IR sensors. (see http://www.maxmax.com/camcorders.htm). BTW, what kind of effect to you want to get ? An colorized image like http://www.jenoptiklos.com/img/323/1/hauptbild.30.bmp or a grayscale, possibly greenish image like http://www.dreamshine.com/images/MaxMax/Sam%20Outcalt/NFF_ir_1.JPG (difficult to see, but the reason why leaves are so bright is because they are warmed by the sunlight; the trunk is less hot. I believe this picture has been taken during the day, which would explain the general bright tone) ?  Emmanuel  Mail Original  De: "Ron Hay" <rhay@...> À: "Game Development Algorithms" <gdalgorithmslist@...> Envoyé: Jeudi 28 Mai 2009 15h18:04 GMT Objet: [Algorithms] Thermal infrared techniques? Anyone have points to papers/tutorials/explanations of some algorithms for rendering a scene as it would appear through a thermal IR camera? As in military operations stuff. Anything ranging from "good enough" to a decent approximation of reality is usable. Thanks!  Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT is a gathering of techside developers & brand creativity professionals. Meet the minds behind Google Creative Lab, Visual Complexity, Processing, & iPhoneDevCamp as they present alongside digital heavyweights like Barbarian Group, R/GA, & Big Spaceship. http://p.sf.net/sfu/creativitycatcom _______________________________________________ GDAlgorithmslist mailing list GDAlgorithmslist@... https://lists.sourceforge.net/lists/listinfo/gdalgorithmslist Archives: http://sourceforge.net/mailarchive/forum.php?forum_name=gdalgorithmslist 
From: Andy Finkenstadt <andyf@si...>  20090528 15:07:51

Ron Hay wrote: > Anyone have points to papers/tutorials/explanations of some algorithms > for rendering a scene as it would appear through a thermal IR camera? > As in military operations stuff. Anything ranging from "good enough" to > a decent approximation of reality is usable. > > Thanks! > > Intuitively, render luminance (0.0  1.0) mapped to green with some overbrightness / glow effect. How do you think that would work? andy 
From: Ron Hay <rhay@cy...>  20090528 14:13:42

Anyone have points to papers/tutorials/explanations of some algorithms for rendering a scene as it would appear through a thermal IR camera? As in military operations stuff. Anything ranging from "good enough" to a decent approximation of reality is usable. Thanks! 
From: Jon Watte <jwatte@gm...>  20090527 04:52:52

Fabian Giesen wrote: > translation nor rotation of the polygon will change its area. So the > remaining area is not helpful at all in comparing which is a better fit. > If the point is that you have many polygons to choose from, then the largest polygon that fits would "fit best." Sincerely, jw 
From: Fabian Giesen <f.giesen@49...>  20090526 15:46:17

> not at all  if you think of the physical world rather than a > mathematical one, this search for 'best fit' is one that a child might > use playing with a set of oddshape blocks and a box. Ask him which > shape 'best fits' in the box and he won't think of scale... The basic point remains though that this is still just a binary test as requested (i.e. using translation and rotation only). Either the other polygon fits into the quad or it doesn't, but when it does, the remaining area is always Area(Quad)Area(Polygon), since neither translation nor rotation of the polygon will change its area. So the remaining area is not helpful at all in comparing which is a better fit. Fabian Giesen 
From: Peter Lipson <peter@to...>  20090526 15:36:29

 I thought I should quote from the problem definition, too: I have different polygons with varying shape and size and I want > to find the polygon and according transformation of the polygon which > best fits it into the given quad.  so it's not a question of "find the tightest bounding quadrilateral on a given polygon". It's "find the polygon that matches the given quad". Peter Lipson wrote: > not at all  if you think of the physical world rather than a > mathematical one, this search for 'best fit' is one that a child might > use playing with a set of oddshape blocks and a box. Ask him which > shape 'best fits' in the box and he won't think of scale... > > Nicholas "Indy" Ray wrote: >> Without scaling this seems to be an odd request... as what defines any >> one fit better then another, so long as the polygon does fit within >> the quad, there lacks a metric for "best" as any fit will take the >> same area and have the same excess area > 
From: Peter Lipson <peter@to...>  20090526 15:33:01

not at all  if you think of the physical world rather than a mathematical one, this search for 'best fit' is one that a child might use playing with a set of oddshape blocks and a box. Ask him which shape 'best fits' in the box and he won't think of scale... Nicholas "Indy" Ray wrote: > Without scaling this seems to be an odd request... as what defines any > one fit better then another, so long as the polygon does fit within > the quad, there lacks a metric for "best" as any fit will take the > same area and have the same excess area 
From: Nicholas \Indy\ Ray <arelius@gm...>  20090525 21:34:12

Except with Scaling you can define best fit to be the fit that takes up the most amount of area, which is a pretty standard metric for best fit, no such standard metric exists without scaling IMO. Nicholas "Indy" Ray On Mon, May 25, 2009 at 2:04 AM, Fabian Giesen <f.giesen@...> wrote: >> Without scaling this seems to be an odd request... as what defines any >> one fit better then another, so long as the polygon does fit within >> the quad, there lacks a metric for "best" as any fit will take the >> same area and have the same excess area. > > Same goes for scaling though  just let the scaling factor run towards 0 > and your metric will look better and better. > > Fabian Giesen > >  > Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT > is a gathering of techside developers & brand creativity professionals. Meet > the minds behind Google Creative Lab, Visual Complexity, Processing, & > iPhoneDevCamp asthey present alongside digital heavyweights like Barbarian > Group, R/GA, & Big Spaceship. http://www.creativitycat.com > _______________________________________________ > GDAlgorithmslist mailing list > GDAlgorithmslist@... > https://lists.sourceforge.net/lists/listinfo/gdalgorithmslist > Archives: > http://sourceforge.net/mailarchive/forum.php?forum_name=gdalgorithmslist > 
From: Fabian Giesen <f.giesen@49...>  20090525 09:04:18

> Without scaling this seems to be an odd request... as what defines any > one fit better then another, so long as the polygon does fit within > the quad, there lacks a metric for "best" as any fit will take the > same area and have the same excess area. Same goes for scaling though  just let the scaling factor run towards 0 and your metric will look better and better. Fabian Giesen 
From: Nicholas \Indy\ Ray <arelius@gm...>  20090525 03:23:15

Without scaling this seems to be an odd request... as what defines any one fit better then another, so long as the polygon does fit within the quad, there lacks a metric for "best" as any fit will take the same area and have the same excess area. Indy On Sun, May 24, 2009 at 3:52 PM, Stefan Dänzer <stefan.daenzer@...> wrote: > Sorry Jon, I stated the allowed transformations incorrectly in my last > email. The following part: > "The allowed transformations which can be applied to the polygon are > translation and scaling" > should read: > The allowed transformations which can be applied to the polygon are > translation and rotation." > Sorry for the confusion. > > On Sun, May 24, 2009 at 6:42 PM, Jon Watte <jwatte@...> wrote: >> >> Stefan Dänzer wrote: >> > size. I have different polygons with varying shape and size and I want >> > to find the polygon and according transformation of the polygon which >> > best fits it into the given quad. The allowed transformations which >> > can be applied to the polygon are translation and scaling. >> > >> >> But you could just as easily try to fit the rectangle around the >> polygon, using translation and rotation, and then just invert that >> transform to go from polygon to rectangle. >> >> In general, I believe you can show that the optimal fit will have one >> side of the polygon parallel with one side of the rectangle. If that is >> indeed the case, a very straightforward algorithm (but slow) would be: >> >> foreach polygon: >> foreach side in the polygon >> for lengthwise and heightwise sides in rectangle >> translate and rotate polygon so that it fits as well as possible >> with the polygon side snug to the rectangle side >> test whether fully inside, and calculate coverage >> >> Then pick the one with the best coverage value while being fully inside. >> To calculate the "snug fit" you rotate the polygon to match the side to >> the rectangle, rotate your frame of reference to make this side "right," >> and then slide it so that the uppermost vertex just touches the >> uppermost side of the rectangle. >> >> Sincerely, >> >> jw >> >> >> >>  >> Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT >> is a gathering of techside developers & brand creativity professionals. >> Meet >> the minds behind Google Creative Lab, Visual Complexity, Processing, & >> iPhoneDevCamp asthey present alongside digital heavyweights like Barbarian >> Group, R/GA, & Big Spaceship. http://www.creativitycat.com >> _______________________________________________ >> GDAlgorithmslist mailing list >> GDAlgorithmslist@... >> https://lists.sourceforge.net/lists/listinfo/gdalgorithmslist >> Archives: >> http://sourceforge.net/mailarchive/forum.php?forum_name=gdalgorithmslist > > > >  >  > Stefan Daenzer > Körnerplatz 8 > 04107 Leipzig > > Tel.: +4917661157550 > > "Work like you don't need the money, love like you've never been hurt and > dance like no one is watching."  Randall G Leighton > >  > Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT > is a gathering of techside developers & brand creativity professionals. > Meet > the minds behind Google Creative Lab, Visual Complexity, Processing, & > iPhoneDevCamp asthey present alongside digital heavyweights like Barbarian > Group, R/GA, & Big Spaceship. http://www.creativitycat.com > _______________________________________________ > GDAlgorithmslist mailing list > GDAlgorithmslist@... > https://lists.sourceforge.net/lists/listinfo/gdalgorithmslist > Archives: > http://sourceforge.net/mailarchive/forum.php?forum_name=gdalgorithmslist > 
From: Jon Watte <jwatte@gm...>  20090525 03:02:26

That's what I actually thought, so that's what I answered. Sincerely, jw Stefan Dänzer wrote: > Sorry Jon, I stated the allowed transformations incorrectly in my last > email. The following part: > > "The allowed transformations which can be applied to the polygon are > translation and scaling" > > should read: > > The allowed transformations which can be applied to the polygon are > translation and rotation." > > Sorry for the confusion. > > On Sun, May 24, 2009 at 6:42 PM, Jon Watte <jwatte@... > <mailto:jwatte@...>> wrote: > > Stefan Dänzer wrote: > > size. I have different polygons with varying shape and size and > I want > > to find the polygon and according transformation of the polygon > which > > best fits it into the given quad. The allowed transformations which > > can be applied to the polygon are translation and scaling. > > > > But you could just as easily try to fit the rectangle around the > polygon, using translation and rotation, and then just invert that > transform to go from polygon to rectangle. > > In general, I believe you can show that the optimal fit will have one > side of the polygon parallel with one side of the rectangle. If > that is > indeed the case, a very straightforward algorithm (but slow) would be: > > foreach polygon: > foreach side in the polygon > for lengthwise and heightwise sides in rectangle > translate and rotate polygon so that it fits as well as possible > with the polygon side snug to the rectangle side > test whether fully inside, and calculate coverage > > Then pick the one with the best coverage value while being fully > inside. > To calculate the "snug fit" you rotate the polygon to match the > side to > the rectangle, rotate your frame of reference to make this side > "right," > and then slide it so that the uppermost vertex just touches the > uppermost side of the rectangle. > > Sincerely, > > jw > > >  > Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT > is a gathering of techside developers & brand creativity > professionals. Meet > the minds behind Google Creative Lab, Visual Complexity, Processing, & > iPhoneDevCamp asthey present alongside digital heavyweights like > Barbarian > Group, R/GA, & Big Spaceship. http://www.creativitycat.com > _______________________________________________ > GDAlgorithmslist mailing list > GDAlgorithmslist@... > <mailto:GDAlgorithmslist@...> > https://lists.sourceforge.net/lists/listinfo/gdalgorithmslist > Archives: > http://sourceforge.net/mailarchive/forum.php?forum_name=gdalgorithmslist > > > > >  >  > Stefan Daenzer > Körnerplatz 8 > 04107 Leipzig > > Tel.: +4917661157550 > > "Work like you don't need the money, love like you've never been hurt > and dance like no one is watching."  Randall G Leighton >  > >  > Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT > is a gathering of techside developers & brand creativity professionals. Meet > the minds behind Google Creative Lab, Visual Complexity, Processing, & > iPhoneDevCamp asthey present alongside digital heavyweights like Barbarian > Group, R/GA, & Big Spaceship. http://www.creativitycat.com >  > > _______________________________________________ > GDAlgorithmslist mailing list > GDAlgorithmslist@... > https://lists.sourceforge.net/lists/listinfo/gdalgorithmslist > Archives: > http://sourceforge.net/mailarchive/forum.php?forum_name=gdalgorithmslist 
From: Stefan Dänzer <stefan.daenzer@gm...>  20090524 22:53:11

Sorry Jon, I stated the allowed transformations incorrectly in my last email. The following part: "The allowed transformations which can be applied to the polygon are translation and scaling" should read: The allowed transformations which can be applied to the polygon are translation and rotation." Sorry for the confusion. On Sun, May 24, 2009 at 6:42 PM, Jon Watte <jwatte@...> wrote: > Stefan Dänzer wrote: > > size. I have different polygons with varying shape and size and I want > > to find the polygon and according transformation of the polygon which > > best fits it into the given quad. The allowed transformations which > > can be applied to the polygon are translation and scaling. > > > > But you could just as easily try to fit the rectangle around the > polygon, using translation and rotation, and then just invert that > transform to go from polygon to rectangle. > > In general, I believe you can show that the optimal fit will have one > side of the polygon parallel with one side of the rectangle. If that is > indeed the case, a very straightforward algorithm (but slow) would be: > > foreach polygon: > foreach side in the polygon > for lengthwise and heightwise sides in rectangle > translate and rotate polygon so that it fits as well as possible > with the polygon side snug to the rectangle side > test whether fully inside, and calculate coverage > > Then pick the one with the best coverage value while being fully inside. > To calculate the "snug fit" you rotate the polygon to match the side to > the rectangle, rotate your frame of reference to make this side "right," > and then slide it so that the uppermost vertex just touches the > uppermost side of the rectangle. > > Sincerely, > > jw > > > >  > Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT > is a gathering of techside developers & brand creativity professionals. > Meet > the minds behind Google Creative Lab, Visual Complexity, Processing, & > iPhoneDevCamp asthey present alongside digital heavyweights like Barbarian > Group, R/GA, & Big Spaceship. http://www.creativitycat.com > _______________________________________________ > GDAlgorithmslist mailing list > GDAlgorithmslist@... > https://lists.sourceforge.net/lists/listinfo/gdalgorithmslist > Archives: > http://sourceforge.net/mailarchive/forum.php?forum_name=gdalgorithmslist >   Stefan Daenzer Körnerplatz 8 04107 Leipzig Tel.: +4917661157550 "Work like you don't need the money, love like you've never been hurt and dance like no one is watching."  Randall G Leighton 
From: Osman, Brian <BOsman@vv...>  20090524 17:20:57

So what's your precise metric for "best fit"? Earlier you mentioned the area of the polygon that doesn't fit into the quad... But if scale (even uniform scale) is a permitted transformation then that must only be part of the metric. It's trivial to scale all polygons down to a point, such that they all fit perfectly into ANY quadrilateral. Brian Original Message From: Stefan Dänzer [mailto:stefan.daenzer@...] Sent: Saturday, May 23, 2009 12:08 PM To: Game Development Algorithms Subject: Re: [Algorithms] Best fit of polygon inside another polygon Hi Emil, that's not exactly the problem I am trying to solve. Maybe I have stated it incorrectly. In my case the surrounding quad is of fixed size. I have different polygons with varying shape and size and I want to find the polygon and according transformation of the polygon which best fits it into the given quad. The allowed transformations which can be applied to the polygon are translation and scaling. regards, Stefan On Fri, May 22, 2009 at 8:27 PM, Emil Persson <humus@...> wrote: > I'm tired and I have a headache, but if I understand your problem right then > it sounds like a special case of a problem I just solved last night and > wrote a tool for: > > http://www.humus.name/index.php?page=News&ID=266 > > > > So you'd just input your polygon directly (instead of inputting a particle > texture and generate a polygon from that) and optimize for 4 vertices and > that would solve it, no? > > > > Emil > > > > > > From: Stefan.Daenzer@... [mailto:Stefan.Daenzer@...] > Sent: 22 May 2009 14:59 > To: Game Development Algorithms > Subject: [Algorithms] Best fit of polygon inside another polygon > > > > Hi, > > I've been thinking about an algorithm which fits a given polygon into a > quad. I've stumbled upon this while trying to fit the largest possible > polygon out of a set of different polygons into a quadliteral. What I want > to find is the bestfitpolygon which can be contained completely in the > quadliteral. The polygon and quad can be assumed to be convex. An nice > feature would be to calculate the error as a function of the area which > doesn't fit into the quad for every polygon I throw at the quad. > > I'm working in 2D right now, but might want to expand the problem for a > later application into a 3D case (fit a polyhedra into a hexahedron). > > Any ideas how to solve this problem? > > Stefan > >  > Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT > is a gathering of techside developers & brand creativity professionals. > Meet > the minds behind Google Creative Lab, Visual Complexity, Processing, & > iPhoneDevCamp asthey present alongside digital heavyweights like Barbarian > Group, R/GA, & Big Spaceship. http://www.creativitycat.com > _______________________________________________ > GDAlgorithmslist mailing list > GDAlgorithmslist@... > https://lists.sourceforge.net/lists/listinfo/gdalgorithmslist > Archives: > http://sourceforge.net/mailarchive/forum.php?forum_name=gdalgorithmslist >   Stefan Daenzer Körnerplatz 8 04107 Leipzig Tel.: +4917661157550 "Work like you don't need the money, love like you've never been hurt and dance like no one is watching."  Randall G Leighton  Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT is a gathering of techside developers & brand creativity professionals. Meet the minds behind Google Creative Lab, Visual Complexity, Processing, & iPhoneDevCamp asthey present alongside digital heavyweights like Barbarian Group, R/GA, & Big Spaceship. http://www.creativitycat.com _______________________________________________ GDAlgorithmslist mailing list GDAlgorithmslist@... https://lists.sourceforge.net/lists/listinfo/gdalgorithmslist Archives: http://sourceforge.net/mailarchive/forum.php?forum_name=gdalgorithmslist 
From: Jon Watte <jwatte@gm...>  20090524 16:42:21

Stefan Dänzer wrote: > size. I have different polygons with varying shape and size and I want > to find the polygon and according transformation of the polygon which > best fits it into the given quad. The allowed transformations which > can be applied to the polygon are translation and scaling. > But you could just as easily try to fit the rectangle around the polygon, using translation and rotation, and then just invert that transform to go from polygon to rectangle. In general, I believe you can show that the optimal fit will have one side of the polygon parallel with one side of the rectangle. If that is indeed the case, a very straightforward algorithm (but slow) would be: foreach polygon: foreach side in the polygon for lengthwise and heightwise sides in rectangle translate and rotate polygon so that it fits as well as possible with the polygon side snug to the rectangle side test whether fully inside, and calculate coverage Then pick the one with the best coverage value while being fully inside. To calculate the "snug fit" you rotate the polygon to match the side to the rectangle, rotate your frame of reference to make this side "right," and then slide it so that the uppermost vertex just touches the uppermost side of the rectangle. Sincerely, jw 
From: Stefan Dänzer <stefan.daenzer@gm...>  20090523 16:08:52

Hi Emil, that's not exactly the problem I am trying to solve. Maybe I have stated it incorrectly. In my case the surrounding quad is of fixed size. I have different polygons with varying shape and size and I want to find the polygon and according transformation of the polygon which best fits it into the given quad. The allowed transformations which can be applied to the polygon are translation and scaling. regards, Stefan On Fri, May 22, 2009 at 8:27 PM, Emil Persson <humus@...> wrote: > I’m tired and I have a headache, but if I understand your problem right then > it sounds like a special case of a problem I just solved last night and > wrote a tool for: > > http://www.humus.name/index.php?page=News&ID=266 > > > > So you’d just input your polygon directly (instead of inputting a particle > texture and generate a polygon from that) and optimize for 4 vertices and > that would solve it, no? > > > > Emil > > > > > > From: Stefan.Daenzer@... [mailto:Stefan.Daenzer@...] > Sent: 22 May 2009 14:59 > To: Game Development Algorithms > Subject: [Algorithms] Best fit of polygon inside another polygon > > > > Hi, > > I've been thinking about an algorithm which fits a given polygon into a > quad. I've stumbled upon this while trying to fit the largest possible > polygon out of a set of different polygons into a quadliteral. What I want > to find is the bestfitpolygon which can be contained completely in the > quadliteral. The polygon and quad can be assumed to be convex. An nice > feature would be to calculate the error as a function of the area which > doesn't fit into the quad for every polygon I throw at the quad. > > I'm working in 2D right now, but might want to expand the problem for a > later application into a 3D case (fit a polyhedra into a hexahedron). > > Any ideas how to solve this problem? > > Stefan > >  > Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT > is a gathering of techside developers & brand creativity professionals. > Meet > the minds behind Google Creative Lab, Visual Complexity, Processing, & > iPhoneDevCamp asthey present alongside digital heavyweights like Barbarian > Group, R/GA, & Big Spaceship. http://www.creativitycat.com > _______________________________________________ > GDAlgorithmslist mailing list > GDAlgorithmslist@... > https://lists.sourceforge.net/lists/listinfo/gdalgorithmslist > Archives: > http://sourceforge.net/mailarchive/forum.php?forum_name=gdalgorithmslist >   Stefan Daenzer Körnerplatz 8 04107 Leipzig Tel.: +4917661157550 "Work like you don't need the money, love like you've never been hurt and dance like no one is watching."  Randall G Leighton 
From: Emil Persson <humus@co...>  20090522 18:28:31

I'm tired and I have a headache, but if I understand your problem right then it sounds like a special case of a problem I just solved last night and wrote a tool for: http://www.humus.name/index.php?page=News <http://www.humus.name/index.php?page=News&ID=266>; &ID=266 So you'd just input your polygon directly (instead of inputting a particle texture and generate a polygon from that) and optimize for 4 vertices and that would solve it, no? Emil From: Stefan.Daenzer@... [mailto:Stefan.Daenzer@...] Sent: 22 May 2009 14:59 To: Game Development Algorithms Subject: [Algorithms] Best fit of polygon inside another polygon Hi, I've been thinking about an algorithm which fits a given polygon into a quad. I've stumbled upon this while trying to fit the largest possible polygon out of a set of different polygons into a quadliteral. What I want to find is the bestfitpolygon which can be contained completely in the quadliteral. The polygon and quad can be assumed to be convex. An nice feature would be to calculate the error as a function of the area which doesn't fit into the quad for every polygon I throw at the quad. I'm working in 2D right now, but might want to expand the problem for a later application into a 3D case (fit a polyhedra into a hexahedron). Any ideas how to solve this problem? Stefan 
From: Robin Green <robin.green@gm...>  20090522 17:33:41

On Fri, May 22, 2009 at 8:41 AM, Peter Lipson <peter@...> wrote: > sounds like a question from one of my takehome final exams.... > > Welcome to the world of R&D, where it's like taking an exam every day of the week. Only there are no right answers, no scores at the end, and it's not clear whether the question is even possible.  R. 
From: Peter Lipson <peter@to...>  20090522 16:08:17

sounds like a question from one of my takehome final exams.... Stefan.Daenzer@... wrote: > Hi, > > I've been thinking about an algorithm which fits a given polygon into > a quad. I've stumbled upon this while trying to fit the largest > possible polygon out of a set of different polygons into a > quadliteral. What I want to find is the bestfitpolygon which can be > contained completely in the quadliteral. The polygon and quad can be > assumed to be convex. An nice feature would be to calculate the error > as a function of the area which doesn't fit into the quad for every > polygon I throw at the quad. > > I'm working in 2D right now, but might want to expand the problem for > a later application into a 3D case (fit a polyhedra into a hexahedron). > > Any ideas how to solve this problem? > > Stefan >  > >  > Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT > is a gathering of techside developers & brand creativity professionals. Meet > the minds behind Google Creative Lab, Visual Complexity, Processing, & > iPhoneDevCamp asthey present alongside digital heavyweights like Barbarian > Group, R/GA, & Big Spaceship. http://www.creativitycat.com >  > > _______________________________________________ > GDAlgorithmslist mailing list > GDAlgorithmslist@... > https://lists.sourceforge.net/lists/listinfo/gdalgorithmslist > Archives: > http://sourceforge.net/mailarchive/forum.php?forum_name=gdalgorithmslist 
From: Fabian Giesen <f.giesen@49...>  20090522 13:15:13

Stefan.Daenzer@... wrote: > Hi, > > I've been thinking about an algorithm which fits a given polygon into a > quad. I've stumbled upon this while trying to fit the largest possible > polygon out of a set of different polygons into a quadliteral. What I > want to find is the bestfitpolygon which can be contained completely > in the quadliteral. The polygon and quad can be assumed to be convex. An > nice feature would be to calculate the error as a function of the area > which doesn't fit into the quad for every polygon I throw at the quad. > > I'm working in 2D right now, but might want to expand the problem for a > later application into a 3D case (fit a polyhedra into a hexahedron). > > Any ideas how to solve this problem? > > Stefan Which transformations are allowed? "Only translations", "translations and rotations", "translations, rotations and uniform scaling" and "general affine transformation" are all sensible choices but lead to very different approaches. Also, is the quad a general convex quad, or is it a rectangle or parallelogram? Kind regards, Fabian Giesen 
From: <Stefan.Daenzer@gm...>  20090522 12:58:57

Hi, I've been thinking about an algorithm which fits a given polygon into a quad. I've stumbled upon this while trying to fit the largest possible polygon out of a set of different polygons into a quadliteral. What I want to find is the bestfitpolygon which can be contained completely in the quadliteral. The polygon and quad can be assumed to be convex. An nice feature would be to calculate the error as a function of the area which doesn't fit into the quad for every polygon I throw at the quad. I'm working in 2D right now, but might want to expand the problem for a later application into a 3D case (fit a polyhedra into a hexahedron). Any ideas how to solve this problem? Stefan 
From: <christer_ericson@pl...>  20090521 04:13:43

Manolache Adrian wrote: > I checked and there are a lot of cases when vertices are very close to > a lot of planes, and this causes problems when splitting with these > planes. If the vertex is sufficiently close to a plane it should be considered ON the plane; this is what it meant by a fat/thick plane. It sounds to me that you might not be correctly handling the thick planes. The introduction of thick planes changes not only how you clip/split polygons to the plane but also how you classify polygons w.r.t. being in front/on/behind the plane. You can find a short outline of the problems in my GDC lecture on robustness: http://realtimecollisiondetection.net/pubs/ There's a lot more detail in my book on both splitting and classifying to thick planes (pp 364373). Christer Ericson, Director of Tools and Technology Sony Computer Entertainment, Santa Monica http://realtimecollisiondetection.net/blog/ 
From: Manolache Adrian <prog_ady@ya...>  20090521 03:12:18

The bsp construction is part of a bigger application. Actually it's part of my bachelor's thesis. I chose to implement among others a full BSP PVS 3D engine.This translates in the construction of a solid node leafy bsp tree, automatic portal generation and finally the pvs calculation, rle encoded and further a merge between coplanar adjiacent polygons in every leaf. As a plus i also implemented a portal renderer using the automatically generated portals(it's not lightning fast due to the big number of portals but it was fun to do). The BSP/PVS 3D engine works flawlessly until now on 3 levels with tri counts ranging from 1000 to 6000. It seems i have to tweak the EPSILON used when clipping and classifying. I found that an epsilon of 0.01 works well on these three levels because of the range of values in them. The problem arises on the 4th level that has about 15000 triangles on which the construction of the bsp tree fails. I checked and there are a lot of cases when vertices are very close to a lot of planes, and this causes problems when splitting with these planes. The construction of the bsp tree fails because polygons like this one arrive in a back leaf and being used as a splitter in the past: (29.467429, 91.150700, 145.998993) (29.500788, 91.204792, 146.329036) (29.500788, 91.151931, 145.998993) I have run of ideas trying to tweak the epsilon for this level. Implementation details: 1.0 Every clipped polygon inherits the normal of the initial polygon 2.0 When clipping edges, Intersection points are calculated in a consistent manner (from front of the plane to back, all the time). 3.0 I treat the planes as being fat. 4.0' I'm using doubles when performing calculations. I am not quite sure how to tackle the other two things mentioned by Chris (4 and 5). > Overall though, WHY are you using a BSP tree? There are > some valid uses for them, but for a lot of applications > they are a bad choice of data structure! One of my favorite games was quake and i wanted to explore similar techniques used by it and second of all i believe these approaches(or a modification of them) may still be useful on less powerful machines (handheld devices) when dealing with interior, dungeon like environments. I would guess that nowadays portal engines are the norm for interior environments(with portals placed by the artists). 