Profile tool - profile line bigger than grid area - strange results

  • Jan Helebrant

    Jan Helebrant - 2012-10-19

    I have plenty of grids with cartesian coordinates and following extent:

    [-20.000000] - [20.000000] = [40.000000]
    [-10.000000] - [50.000000] = [60.000000]

    I need to create various profiles for particular grids which all has to intersect point (0;0) but have different orientation. I have to compare these profiles so I calculated the profile point coordinates to have 30 m on shorter and 50 m on longer side (just to be sure the profile will always take all the data within the direction).

    However, if I use the profile tool to get the data, I got data probably only for a part of the profile while I expected zeros or some no-data for parts of the profile outside the grid area.

    Is there any way to get the correct data or do I have to somehow recalculate the distance extent of the profile and add the zeros manually to match the standard extent?

    thanks much


  • Volker Wichmann

    Volker Wichmann - 2012-10-22


    I just had a quick look at the sources, seems like all profile coordinates outside the grid extent are simply discarded. I don't know if this explains the effects you observe.

  • Jan Helebrant

    Jan Helebrant - 2012-10-30

    Thanks Volker,
    I was afraid it is this issue. Yes it explains the strange shift of my value distribution on the profile.

    I temporarily solved this by using a measure tool to get length of the first profile section outside the grid system (have 0,5 m grid so my measuring is enough accurate) and then manually move the profile data in LibreOffice Calc (where I also do further analyses) to the right distance.

    Not much comfortable for me, but works.


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