## geotools-gt2-users

 [Geotools-gt2-users] Problem with converting between coordinates and matrix index From: Rasmossen - 2011-11-14 23:32:27 ```Hello! I'm doing a school work where we are making a robot scan a "game area" and register obstacles into a raster. I get the coordinates in RT90: I have done following steps: * Made an CoordinateReferenceSystem (crs) from right EPSG code. * Found the lower left corner / top right corner and made a ReferencedEnvelope (env). * Built a matrix float[height][width] and then constructed an GridCoverage2D(cov) from the crs and env. What i want now is to take an coordinate make it to the right index for the matrix so i can build up an cost matrix which will be used to find the shortest part from point a and point b. The problem i find is that the (x,y) i get from GridCoverage2D.getGridGeometry().gridToWorld() aren't right. I think i get the (x,y) in the GridCoverage2D raster and not in the matrix but shouldn't they be the same since i use the matrix to make the coverage? I hope you can help me solve my problem since i will use it both to point out the obstacles and the "game area". Regards Rasmus -- View this message in context: http://osgeo-org.1803224.n2.nabble.com/Problem-with-converting-between-coordinates-and-matrix-index-tp6994581p6994581.html Sent from the geotools-gt2-users mailing list archive at Nabble.com. ```
 Re: [Geotools-gt2-users] Problem with converting between coordinates and matrix index From: Michael Bedward - 2011-11-15 00:29:47 ```Hi Rasmus, The first thing to check is that you have your x and y dimensions the right way round. Your float matrix should have [row][col] layout, ie. the first dimension corresponds to world Y axis and the second to world X axis. Next, your CRS should be constructed so that you get X (longitude), Y (latitude) order. RT90 has Y,X order so to get it the right way round you should do: CRS.decode("EPSG:4124", true). Hope this helps. If not, please post a small example (code + results) that illustrates the problem. Michael On 15 November 2011 10:32, Rasmossen wrote: > Hello! > > I'm doing a school work where we are making a robot scan a "game area" and > register obstacles into a raster. > > I get the coordinates in RT90: > I have done following steps: > > * Made an CoordinateReferenceSystem (crs) from right EPSG code. > * Found the lower left corner / top right corner and made a > ReferencedEnvelope (env). > * Built a matrix float[height][width] and then constructed an > GridCoverage2D(cov) from the crs and env. > > What i want now is to take an coordinate make it to the right index for the > matrix so i can build up an cost matrix which will be used to find the > shortest part from point a and point b. > > The problem i find is that the (x,y) i get from > GridCoverage2D.getGridGeometry().gridToWorld() aren't right. > I think i get the (x,y) in the GridCoverage2D raster and not in the matrix > but shouldn't they be the same since i use the matrix to make the coverage? > > I hope you can help me solve my problem since i will use it both to point > out the obstacles and the "game area". > > Regards > Rasmus > > -- > View this message in context: http://osgeo-org.1803224.n2.nabble.com/Problem-with-converting-between-coordinates-and-matrix-index-tp6994581p6994581.html > Sent from the geotools-gt2-users mailing list archive at Nabble.com. > > ------------------------------------------------------------------------------ > RSA(R) Conference 2012 > Save \$700 by Nov 18 > Register now > http://p.sf.net/sfu/rsa-sfdev2dev1 > _______________________________________________ > Geotools-gt2-users mailing list > Geotools-gt2-users@... > https://lists.sourceforge.net/lists/listinfo/geotools-gt2-users > ```