Re: [gdal-dev] gdal_translate to TIFF -- color mismatch
Le jeudi 15 décembre 2011 18:08:26, mlade...@distributel.net a écrit : Hi all, I am trying to use gdal_translate to convert a .grd file (Northwood/VerticalMapper format) to TIFF. However, the colors in the translated file don't seem to be interpolated correctly based on the color scheme, for values near the end of the range. Here is a link to the original GRD, as well as the exported TIFFs (small download, only 200K): http://dl.dropbox.com/u/53500018/GdalQuestion.zip The GdalTranslateExport.tif file was produced with the command gdal_translate -b 1 -b 2 -b 3 C:\source\Ottawa_east_DEM30m_trim_copy.grd C:\temp\GdalTranslateExport.tif. Notice the top and bottom areas of the image: they are yellow. For comparison, take a look at the NativeExport.tif file in the same package. The top and bottom areas are orange, as they should be. The NativeExport.tif file was produced by Pitney Bowes MapInfo. Here is the color scheme for the GRD: http://www.smugmug.com/photos/i-bRZ879w/0/X3/i-bRZ879w-X3.jpg Notice that the thresholds are 70 for yellow, and 161 for orange. Well, the values at the top and bottom are in the high 130s/low 140s. So they should be interpolated close to orange, not yellow. Therefore the NativeExport.tif is correct, and the gdal_translate export is incorrect. I have also tried changing the thresholds, and as soon as I change the orange threshold to be below the maximum actual value in the GRD (let's say 144), the gdal_translate export shows the orange shades. Good analysis. There was indeed a bug in the way the end of the color palette is interpolated if the maximum z value is below a threshold of the color scheme. See http://trac.osgeo.org/gdal/ticket/4395 for the fix (a simple typo) So, it seems there might be a bug in gdal_translate where color values are not interpolated correctly for thresholds that fall outside of the range of actual values? Or is there a way to make gdal_translate behave the way that I want with some different command line options? Regards, Mladen Gavrilovic P.S. For convenience, here is a gallery with the TIFFs converted to JPEG (difference is still obvious), and the color scheme: http://smu.gs/vMEemF P.P.S Version of GDAL is 1.8.1 This message was sent using Distributel Webmail. Ce message a été envoyé à partir de la Messagerie Web Distributel. ___ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev ___ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
Re: [gdal-dev] gdal_translate to TIFF -- color mismatch
Wow, that was fast. Thanks! I see that the fix is in 1.8.2... Do you know will this be a separate release or will the fixes be merged into 1.9.0? I ask because I see some recent discussions suggesting that 1.9.0 may be released by the end of the year. Thanks again for the quick response, Mladen Quoting Even Rouault even.roua...@mines-paris.org: Le jeudi 15 décembre 2011 18:08:26, mlade...@distributel.net a écrit : Hi all, I am trying to use gdal_translate to convert a .grd file (Northwood/VerticalMapper format) to TIFF. However, the colors in the translated file don't seem to be interpolated correctly based on the color scheme, for values near the end of the range. Here is a link to the original GRD, as well as the exported TIFFs (small download, only 200K): http://dl.dropbox.com/u/53500018/GdalQuestion.zip The GdalTranslateExport.tif file was produced with the command gdal_translate -b 1 -b 2 -b 3 C:\source\Ottawa_east_DEM30m_trim_copy.grd C:\temp\GdalTranslateExport.tif. Notice the top and bottom areas of the image: they are yellow. For comparison, take a look at the NativeExport.tif file in the same package. The top and bottom areas are orange, as they should be. The NativeExport.tif file was produced by Pitney Bowes MapInfo. Here is the color scheme for the GRD: http://www.smugmug.com/photos/i-bRZ879w/0/X3/i-bRZ879w-X3.jpg Notice that the thresholds are 70 for yellow, and 161 for orange. Well, the values at the top and bottom are in the high 130s/low 140s. So they should be interpolated close to orange, not yellow. Therefore the NativeExport.tif is correct, and the gdal_translate export is incorrect. I have also tried changing the thresholds, and as soon as I change the orange threshold to be below the maximum actual value in the GRD (let's say 144), the gdal_translate export shows the orange shades. Good analysis. There was indeed a bug in the way the end of the color palette is interpolated if the maximum z value is below a threshold of the color scheme. See http://trac.osgeo.org/gdal/ticket/4395 for the fix (a simple typo) So, it seems there might be a bug in gdal_translate where color values are not interpolated correctly for thresholds that fall outside of the range of actual values? Or is there a way to make gdal_translate behave the way that I want with some different command line options? Regards, Mladen Gavrilovic P.S. For convenience, here is a gallery with the TIFFs converted to JPEG (difference is still obvious), and the color scheme: http://smu.gs/vMEemF P.P.S Version of GDAL is 1.8.1 This message was sent using Distributel Webmail. Ce message a été envoyé à partir de la Messagerie Web Distributel. ___ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev This message was sent using Distributel Webmail. Ce message a été envoyé à partir de la Messagerie Web Distributel. ___ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
Re: [gdal-dev] gdal_translate to TIFF -- color mismatch
Le jeudi 15 décembre 2011 23:32:14, mlade...@distributel.net a écrit : Wow, that was fast. Thanks! I see that the fix is in 1.8.2... Do you know will this be a separate release or will the fixes be merged into 1.9.0? I ask because I see some recent discussions suggesting that 1.9.0 may be released by the end of the year. The fix also went to trunk (1.9.0) of course (*). And 1.9.0 will likely be released before 1.8.2 indeed. (*) Trac has no way to specify multiple target milestones, so I tend to indicate the milestone corresponding to the stable branch if it has been applied there too. The general rule being that all fixes that go to the stable branch go to trunk too. ___ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
