# How to generate a lat/long geotiff with grdimage **URL:** \ **Category:** Q&A\ **Created:** [April 9, 2024, 12:42am UTC](https://forum.generic-mapping-tools.org/t/how-to-generate-a-lat-long-geotiff-with-grdimage/4780 "2024-04-09T00:42:47Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Brent](https://avatars.discourse-cdn.com/v4/letter/b/ec9cab/32.png) [@Brent](https://forum.generic-mapping-tools.org/u/Brent)\ **Post date:** [April 9, 2024, 12:42am UTC](https://forum.generic-mapping-tools.org/t/how-to-generate-a-lat-long-geotiff-with-grdimage/4780/1 "2024-04-09T00:42:47Z")
Hi, I\m trying to generate an unprojected geotiff image with grdimage. The image is a global relief map, including GEBCO & terrain data. I get a good looking image, but can’t get the georeferencing correct. I want the coords to be in epsg:4326. I’m trying things like: _gmt grdimage @earth\_gebco\_01m\_p -Rd -Aworld.tiff -JEPSG:4326_ _gmt grdimage @earth\_gebco\_01m\_p -R-180/180/-85/85 -Aworld.tiff -J"+proj=lonlat +datum=WGS84" +no\_defs_ But the output image has no CRS and the Y coords seem to be pixel counts, not latitudes. I have set GDAL\_DATA to /usr/share/gdal/ which is where all the GDAL csv files seem to be located. I’m getting the error: ERROR 10: Pointer ‘hTransform’ is NULL in ‘OCTTransform’. repeatedly, but I don’t know why. It seems to relate to a bad EPSG code… Any suggestions appreciated… ---
**Author:** ![Joaquim](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/joaquim/32/16_2.png) [@Joaquim](https://forum.generic-mapping-tools.org/u/Joaquim)\ **Post date:** [April 9, 2024, 10:40am UTC](https://forum.generic-mapping-tools.org/t/how-to-generate-a-lat-long-geotiff-with-grdimage/4780/2 "2024-04-09T10:40:48Z")
No idea. It works for me. Did not try the `@earth_gebco_01m_p` because don’t want to download it but tried with `@earth_relief_01m_p` ```auto # On Win grdimage @earth_gebco_02m_p -Rd -Aworld.tiff -JEPSG:4326 grdimage @earth_relief_01m_p -Rd -Aworld.tiff -JEPSG:4326 # On WSL gmt grdimage @earth_gebco_10m_p -Rd -Aworld.tiff -JEPSG:4326 ``` An old GMT version? EDIT: Yes, I don’t see a projection info when a do gdalinfo but can open the file files in Mirone and QGis ---
**Author:** ![mkononets](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/mkononets/32/4029_2.png) [@mkononets](https://forum.generic-mapping-tools.org/u/mkononets)\ **Post date:** [April 9, 2024, 11:17am UTC](https://forum.generic-mapping-tools.org/t/how-to-generate-a-lat-long-geotiff-with-grdimage/4780/3 "2024-04-09T11:17:13Z")
as a possible workaround, `gdal_translate` and `gdal_edit` have an option to assign a crs to a grid, `-a_srs` `gmt grdedit` can do it too, using `-J...` as far as I can understand. ---
**Author:** ![Joaquim](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/joaquim/32/16_2.png) [@Joaquim](https://forum.generic-mapping-tools.org/u/Joaquim)\ **Post date:** [April 9, 2024, 12:42pm UTC](https://forum.generic-mapping-tools.org/t/how-to-generate-a-lat-long-geotiff-with-grdimage/4780/4 "2024-04-09T12:42:17Z")
The whole situation is confuse and clearly need improvements. For example this (Mollweide) works and stores the SRS, but it requires setting the map width when that is not needed. ```auto gmt grdimage @earth_relief_10m_p -Aworld.tiff -JW15 ``` And If I try with a proj4 string it errors. For map making we need to be able to convert from proj/WKT syntax in order to be able to create the frames, but with -A that is not the case so one should be able to pass the proj4 string or EPSG without doing a round trip to the GMT projection machinery. ---
**Author:** ![Brent](https://avatars.discourse-cdn.com/v4/letter/b/ec9cab/32.png) [@Brent](https://forum.generic-mapping-tools.org/u/Brent)\ **Post date:** [April 9, 2024, 7:04pm UTC](https://forum.generic-mapping-tools.org/t/how-to-generate-a-lat-long-geotiff-with-grdimage/4780/5 "2024-04-09T19:04:53Z")
Thanks Joaquim, I can open the output image in QGIS fine, but it is not correctly geo-located. Opening the GSHHG world coastline shapefile at the same time gives two maps on the canvas, they seem to be correctly aligned vertically, so the longitudes are somewhat consistent, but the latitudes are way different. The raster image is a small block at the top of the screen, the vector at the bottom. I was hoping to use GMT to create a set of images/tiles for a global context layer served via WMS on our research vessels, but if the output images are not correctly georeferenced, it is not viable. Brent ---
**Author:** ![Brent](https://avatars.discourse-cdn.com/v4/letter/b/ec9cab/32.png) [@Brent](https://forum.generic-mapping-tools.org/u/Brent)\ **Post date:** [April 9, 2024, 7:06pm UTC](https://forum.generic-mapping-tools.org/t/how-to-generate-a-lat-long-geotiff-with-grdimage/4780/6 "2024-04-09T19:06:36Z")
Thanks for the suggestion, but it is not just the lack of a CRS, the Y coordinates are wrong as well, so just populating the CRS will not solve the problem. Brent ---
**Author:** ![Brent](https://avatars.discourse-cdn.com/v4/letter/b/ec9cab/32.png) [@Brent](https://forum.generic-mapping-tools.org/u/Brent)\ **Post date:** [April 9, 2024, 7:15pm UTC](https://forum.generic-mapping-tools.org/t/how-to-generate-a-lat-long-geotiff-with-grdimage/4780/7 "2024-04-09T19:15:54Z")
Thanks Joaquim, Fresh install of GMT 6.4.4 on fresh Mint Linux setup on Ryzen based server- built from scratch today, then added UbuntuGIS unstable for the package installs via apt. GDAL is v3.8.4. I had issues on my dated desktop so figured a completely new install from the OS up would be more robust… I’m not sure why I keep getting the “ERROR 10: Pointer ‘hTransform’ is NULL…” message (or the first 1000 messages at least). Googling tells me it is a faulty EPSG code, but that does not seem to be the case. Is this a possible clue to another issue on my setup? Thanks, Brent ---
**Author:** ![Joaquim](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/joaquim/32/16_2.png) [@Joaquim](https://forum.generic-mapping-tools.org/u/Joaquim)\ **Post date:** [April 9, 2024, 7:32pm UTC](https://forum.generic-mapping-tools.org/t/how-to-generate-a-lat-long-geotiff-with-grdimage/4780/8 "2024-04-09T19:32:38Z")
> [@Brent](#): > > I can open the output image in QGIS fine, but it is not correctly geo-located. Opening the GSHHG world coastline shapefile at the same time gives two maps on the canvas, they seem to be correctly aligned vertically, so the longitudes are somewhat consistent, but the latitudes are way different. Odd, this is what I get with the Julia wrapper (pure GMT execution, just under other clothes). Some stray warnings that don’t affect the result. Coastlines are plotted right. ```auto julia> I = grdimage("@earth_relief_10m_p", A=true, Vd=1, B=:none, J=4326) Warning: the following options were not consumed in grdimage => [:this_cpt] grdimage @earth_relief_10m_p -J4326 -n+a -A ┌ Warning: Only 'I' for Images.jl and 'BRP' MEM layouts are allowed. └ @ GMT C:\Users\j\.julia\dev\GMT\src\gmt_main.jl:486 A GMTimage object with 3 bands of type UInt8 Pixel node registration used x_min: -180.0 x_max :180.0 x_inc :0.16666666666666666 n_columns :2160 y_min: -90.0 y_max :90.0 y_inc :0.16666666666666666 n_rows :1080 z_min: NaN z_max :NaN Mem layout: TRPa julia> viz(I, coast=true) GMT [WARNING]: gmtapi_change_imagelayout: reordering function for case TRPa -> BRP not yet written. Doing nothing. ``` ![GMTjl_j](https://canada1.discourse-cdn.com/flex047/uploads/gmt/original/2X/e/e188a31953b42e905e3a7dd395eb31469f425674.jpeg) ---
**Author:** ![Joaquim](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/joaquim/32/16_2.png) [@Joaquim](https://forum.generic-mapping-tools.org/u/Joaquim)\ **Post date:** [April 9, 2024, 7:34pm UTC](https://forum.generic-mapping-tools.org/t/how-to-generate-a-lat-long-geotiff-with-grdimage/4780/9 "2024-04-09T19:34:26Z")
> [@Brent](#): > > I’m not sure why I keep getting the “ERROR 10: Pointer ‘hTransform’ is NULL…” message (or the first 1000 messages at least). And you get that error when doing what? Remember that you can also create GeoTIFF images with `psconvert -W` ---
**Author:** ![Brent](https://avatars.discourse-cdn.com/v4/letter/b/ec9cab/32.png) [@Brent](https://forum.generic-mapping-tools.org/u/Brent)\ **Post date:** [April 9, 2024, 7:52pm UTC](https://forum.generic-mapping-tools.org/t/how-to-generate-a-lat-long-geotiff-with-grdimage/4780/10 "2024-04-09T19:52:54Z")
I just ran essentially the same command: gmt grdimage @earth\_relief\_10m\_p -J4326 -n+a -Anext.tiff ![Screenshot at 2024-04-10 07-49-06](https://canada1.discourse-cdn.com/flex047/uploads/gmt/original/2X/4/4162af0392b65e9181148dbe469804c7a611fa09.png) This is the QGIS canvas… the cursor positions are fine for the shapefile, the image is offset. ---
**Author:** ![Brent](https://avatars.discourse-cdn.com/v4/letter/b/ec9cab/32.png) [@Brent](https://forum.generic-mapping-tools.org/u/Brent)\ **Post date:** [April 9, 2024, 7:53pm UTC](https://forum.generic-mapping-tools.org/t/how-to-generate-a-lat-long-geotiff-with-grdimage/4780/11 "2024-04-09T19:53:58Z")
Yep, I will try psconvert as another approach… Thanks!! ---
**Author:** ![Joaquim](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/joaquim/32/16_2.png) [@Joaquim](https://forum.generic-mapping-tools.org/u/Joaquim)\ **Post date:** [April 9, 2024, 8:09pm UTC](https://forum.generic-mapping-tools.org/t/how-to-generate-a-lat-long-geotiff-with-grdimage/4780/12 "2024-04-09T20:09:08Z")
Something else must be going on here. Everything I tried with those .tiff shows correct locations and never a `y` with row numbers. ---
**Author:** ![Brent](https://avatars.discourse-cdn.com/v4/letter/b/ec9cab/32.png) [@Brent](https://forum.generic-mapping-tools.org/u/Brent)\ **Post date:** [April 9, 2024, 8:14pm UTC](https://forum.generic-mapping-tools.org/t/how-to-generate-a-lat-long-geotiff-with-grdimage/4780/13 "2024-04-09T20:14:48Z")
FYI, First cut at psconvert has a similar issue - but the lats seem sensible & the longs are way offset… Will persevere… ---
**Author:** ![Brent](https://avatars.discourse-cdn.com/v4/letter/b/ec9cab/32.png) [@Brent](https://forum.generic-mapping-tools.org/u/Brent)\ **Post date:** [April 9, 2024, 8:17pm UTC](https://forum.generic-mapping-tools.org/t/how-to-generate-a-lat-long-geotiff-with-grdimage/4780/14 "2024-04-09T20:17:34Z")
So something is screwed in my setup? Sigh… That makes it tricky if you can’t replicate it… especially with the brand new install of everything here. Not sure what my next step is - it was all supposed to be relatively easy!!! ---
**Author:** ![mkononets](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/mkononets/32/4029_2.png) [@mkononets](https://forum.generic-mapping-tools.org/u/mkononets)\ **Post date:** [April 9, 2024, 9:13pm UTC](https://forum.generic-mapping-tools.org/t/how-to-generate-a-lat-long-geotiff-with-grdimage/4780/15 "2024-04-09T21:13:52Z")
assigning CRS using `gdal_edit.py` works for me: ```auto gmt grdimage @earth_gebco_10m_p -n+a -Aworld.tiff -J4326 gdal_edit.py -a_srs EPSG:4326 world.tiff gmt begin quick png gmt grdimage world.tiff gmt coast -W -BSWen -Bxa -Bya --MAP_FRAME_TYPE=plain gmt end show ``` ![quick](https://canada1.discourse-cdn.com/flex047/uploads/gmt/original/2X/4/48e4f08cedc0b3bee454eb28339c7b831f210954.jpeg) using `gmt grdedit` quietly fails to assign CRS expressed as `-J4326` to `world.tiff`, but the coastlines appear where they should: ```auto gmt grdimage @earth_gebco_10m_p -n+a -Aworld.tiff -J4326 gmt grdedit world.tiff -J4326 gmt begin quick png gmt grdimage world.tiff gmt coast -W -BSWen -Bxa -Bya --MAP_FRAME_TYPE=plain gmt end show ``` ![quick](https://canada1.discourse-cdn.com/flex047/uploads/gmt/original/2X/f/f660f492479b3dbdf4c2696d47e060d4b16ce258.jpeg) PS my gmt version is 6.5.0, part of my `pygmt` conda/mamba environment. ---
**Author:** ![Joaquim](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/joaquim/32/16_2.png) [@Joaquim](https://forum.generic-mapping-tools.org/u/Joaquim)\ **Post date:** [April 9, 2024, 9:32pm UTC](https://forum.generic-mapping-tools.org/t/how-to-generate-a-lat-long-geotiff-with-grdimage/4780/16 "2024-04-09T21:32:25Z")
> [@mkononets](#): > > using `gmt grdedit` quietly fails to assign CRS expressed as `-J4326` to `world.tiff` To be confirmed but I think `grdedit` works only with netCDF files. ---
**Author:** ![Joaquim](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/joaquim/32/16_2.png) [@Joaquim](https://forum.generic-mapping-tools.org/u/Joaquim)\ **Post date:** [April 9, 2024, 9:46pm UTC](https://forum.generic-mapping-tools.org/t/how-to-generate-a-lat-long-geotiff-with-grdimage/4780/17 "2024-04-09T21:46:24Z")
> [@Brent](#): > > So something is screwed in my setup? Sigh… That makes it tricky if you can’t replicate it… especially with the brand new install of everything here. > > Not sure what my next step is - it was all supposed to be relatively easy!!! Don’t know. Maybe install GMT6.5? Can’t you reproduce this? ```auto C:\v>gmt grdimage @earth_gebco_10m_p -J4326 -P > lixo.ps C:\v>gmt psconvert lixo.ps -W+g Input file size is 1654, 1654 0...10...20...30...40...50...60...70...80...90...100 - done. C:\v>gdalinfo lixo.tiff Driver: GTiff/GeoTIFF Files: lixo.tiff Size is 1654, 1654 Coordinate System is: GEOGCRS["unknown", DATUM["unknown", ELLIPSOID["unknown",6378137,298.257220143428, LENGTHUNIT["metre",1, ID["EPSG",9001]]]], PRIMEM["Greenwich",0, ANGLEUNIT["degree",0.0174532925199433, ID["EPSG",9122]]], CS[ellipsoidal,2], AXIS["latitude",north, ORDER[1], ANGLEUNIT["degree",0.0174532925199433, ID["EPSG",9122]]], AXIS["longitude",east, ORDER[2], ANGLEUNIT["degree",0.0174532925199433, ID["EPSG",9122]]]] Data axis to CRS axis mapping: 2,1 Origin = (-180.217654171704510,90.000000000000000) Pixel Size = (0.217654171705000,-0.108827085852000) Metadata: AREA_OR_POINT=Area Software=GPL Ghostscript GIT PRERELEASE 9.54.0 TIFFTAG_XRESOLUTION=300 TIFFTAG_YRESOLUTION=300 Image Structure Metadata: COMPRESSION=LZW INTERLEAVE=PIXEL Corner Coordinates: Upper Left (-180.2176542, 90.0000000) (180d13' 3.56"W, 90d 0' 0.00"N) Lower Left (-180.2176542, -90.0000000) (180d13' 3.56"W, 90d 0' 0.00"S) Upper Right ( 179.7823458, 90.0000000) (179d46'56.44"E, 90d 0' 0.00"N) Lower Right ( 179.7823458, -90.0000000) (179d46'56.44"E, 90d 0' 0.00"S) Center ( -0.2176542, 0.0000000) ( 0d13' 3.56"W, 0d 0' 0.00"N) Band 1 Block=256x256 Type=Byte, ColorInterp=Red Band 2 Block=256x256 Type=Byte, ColorInterp=Green Band 3 Block=256x256 Type=Byte, ColorInterp=Blue ``` ---
**Author:** ![Brent](https://avatars.discourse-cdn.com/v4/letter/b/ec9cab/32.png) [@Brent](https://forum.generic-mapping-tools.org/u/Brent)\ **Post date:** [April 9, 2024, 10:35pm UTC](https://forum.generic-mapping-tools.org/t/how-to-generate-a-lat-long-geotiff-with-grdimage/4780/18 "2024-04-09T22:35:20Z")
Firstly, thanks heaps for your help. It really is appreciated!!! Will try what you suggest - however - I just built a Win10 VM on the Mint box. Installed Miniconda, GMT & GDAL. Then generated a world.tiff exactly as on Mint Linux (without the GMT prefix). Copied it to the Mint system & opened in QGIS - it overlays perfectly with GSHHG coastline. So something is screwy with the Mint/UbuntuGIS setup… not really a GMT issue if it works perfectly on Windows. Windows is not my preferred platform, but it seems to work. At least I can now do something useful!!! I’m not sure if installing Miniconda on Linux, then gdal in Miniconda & running GMT from the Miniconda shell instead of a bash shell would generate correct geotiffs… Thanks again!!! ---
**Author:** ![Brent](https://avatars.discourse-cdn.com/v4/letter/b/ec9cab/32.png) [@Brent](https://forum.generic-mapping-tools.org/u/Brent)\ **Post date:** [April 9, 2024, 10:47pm UTC](https://forum.generic-mapping-tools.org/t/how-to-generate-a-lat-long-geotiff-with-grdimage/4780/19 "2024-04-09T22:47:19Z")
And I just tried your grdimage/psconvert as above - that also worked, on Linux natively. Gave an image that overlays with QGIS. If I then run: _gdal\_edit.py -a\_crs EPSG:4326 test.tiff_ The geotiff then has the correct CRS metadata embedded, as well as the extents. Which sets me up (I think) to write a script to create the images/tiles I need… Thanks again!!! ---
**Author:** ![mkononets](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/mkononets/32/4029_2.png) [@mkononets](https://forum.generic-mapping-tools.org/u/mkononets)\ **Post date:** [April 9, 2024, 11:28pm UTC](https://forum.generic-mapping-tools.org/t/how-to-generate-a-lat-long-geotiff-with-grdimage/4780/20 "2024-04-09T23:28:30Z")
> [@Brent](#): > > I’m not sure if installing Miniconda on Linux, then gdal in Miniconda & running GMT from the Miniconda shell instead of a bash shell would generate correct geotiffs works for me [Next page](https://forum.generic-mapping-tools.org/t/how-to-generate-a-lat-long-geotiff-with-grdimage/4780.md?page=2)