# Proj4 work with grdproject problem **URL:** \ **Category:** Q&A\ **Created:** [April 19, 2020, 3:52am UTC](https://forum.generic-mapping-tools.org/t/proj4-work-with-grdproject-problem/394 "2020-04-19T03:52:56Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Mark](https://avatars.discourse-cdn.com/v4/letter/m/e9c0ed/32.png) [@Mark](https://forum.generic-mapping-tools.org/u/Mark)\ **Post date:** [April 19, 2020, 3:52am UTC](https://forum.generic-mapping-tools.org/t/proj4-work-with-grdproject-problem/394/1 "2020-04-19T03:52:56Z")
Hello: when run this code: `gmt grdproject AP_14636_FBD_F6850_RT1.dem.grd -J"+proj=utm +zone=58 +south +datum=WGS84 +units=m +no_defs +to+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs" -C -F -Gtest123.grd` it will run forever and not return a result,why ? I try to convert utm grid to wgs84 geodetic coordinates. When I use this command: `gmt grdproject AP_14636_FBD_F6850_RT1.dem.grd -Ju-58/1:1 -C -Fe -I -GAP_14636_FBD_F6850_RT1.dem_Geodetic.grd` it can return a good look result,but also return an Error: `ERROR 1: PROJ: proj_create: Error -13: major axis or radius = 0 or not given` I browsed and it seemed to be caused by PROJ4,Thanks a lot!please help! ---
**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 19, 2020, 6:14pm UTC](https://forum.generic-mapping-tools.org/t/proj4-work-with-grdproject-problem/394/2 "2020-04-19T18:14:28Z")
When I experiment with synthetic data I get this ```auto gmt grdmath -R162/168/-10/0 -I0.1 X Y MUL = lixo.grd gmt grdproject lixo.grd -J"+proj=utm +zone=58 +south +datum=WGS84 +units=m +no_defs" -Glixo_utm.grd gmt grdproject lixo_utm.grd -I -J"+proj=utm +zone=58 +south +datum=WGS84 +units=m +no_defs" -Glixo_geo2.grd First opt_R 164.000000000000/166.000000000000/-6.007148010123/-4.007148010123 1.71944e+09 3.71911e+08 Second opt_R 161.953987660797/-10.013533960436/168.046012339203/0.000000000000r grdproject [WARNING]: Unknown conversion between GMT and GDAL ellipsoid names. Using a generic spherical body. ``` I find that warning worrisome and don’t get it why it’s complaining. Your example also hangs for me (but it’s computing something). ---
**Author:** ![Mark](https://avatars.discourse-cdn.com/v4/letter/m/e9c0ed/32.png) [@Mark](https://forum.generic-mapping-tools.org/u/Mark)\ **Post date:** [April 20, 2020, 6:45am UTC](https://forum.generic-mapping-tools.org/t/proj4-work-with-grdproject-problem/394/3 "2020-04-20T06:45:27Z")
Thanks for reply,I turned a another way,and it work well. > gdalwarp -t\_srs EPSG:4326 -s\_srs EPSG:32758 AP\_15059\_FBS\_F6860\_RT1.dem.tif AP\_15059\_FBS\_F6860\_RT1\_Geodetic.dem.tif As above,I use gdal directly,but I also want to konw why gmt return an error. ---
**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 20, 2020, 11:04am UTC](https://forum.generic-mapping-tools.org/t/proj4-work-with-grdproject-problem/394/4 "2020-04-20T11:04:47Z")
I will try to debug the source of that error message when I have time. ---
**Author:** ![Mark](https://avatars.discourse-cdn.com/v4/letter/m/e9c0ed/32.png) [@Mark](https://forum.generic-mapping-tools.org/u/Mark)\ **Post date:** [April 20, 2020, 1:33pm UTC](https://forum.generic-mapping-tools.org/t/proj4-work-with-grdproject-problem/394/5 "2020-04-20T13:33:28Z")
When I use gdalwarp,it can’t deal with the data in irreagular area. The data in utm projection: ![Snipaste_2020-04-20_21-28-08](https://canada1.discourse-cdn.com/flex047/uploads/gmt/original/1X/627665a40a425e8062c81e02fa532e28dfc4e4e9.png) When I use gdalwarp(`gdalwarp -t_srs EPSG:4326 -s_srs EPSG:32758 source.tif aim.tif`)to get geodetic coordinates in WGS84: ![Snipaste_2020-04-20_21-27-54](https://canada1.discourse-cdn.com/flex047/uploads/gmt/original/1X/4d1e2dc31631d90193d4bd4c5d4b0bd67b7fa224.png) Anyway,Thank you！Joaquim！ ---
**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 20, 2020, 7:50pm UTC](https://forum.generic-mapping-tools.org/t/proj4-work-with-grdproject-problem/394/6 "2020-04-20T19:50:13Z")
Strange that gdalwarp behavior. Note, your case is simple to do with the GMT syntax only. It should be something around (not sure how to set the suthern hemisphere (-Ju58S/1:1 ?) ```auto gmt grdproject -I -C -F -R162/168/-10/0 -Ju-58/1:1 ... ``` ---
**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 22, 2020, 12:12pm UTC](https://forum.generic-mapping-tools.org/t/proj4-work-with-grdproject-problem/394/7 "2020-04-22T12:12:55Z")
@Mark I fixed the ellipsoid names issue (it was a silly bug while comparing text strings), but the other one is tougher. Possibly related to this [https://github.com/GenericMappingTools/gmt/issues/3147](https://github.com/GenericMappingTools/gmt/issues/3147) ---
**Author:** ![Mark](https://avatars.discourse-cdn.com/v4/letter/m/e9c0ed/32.png) [@Mark](https://forum.generic-mapping-tools.org/u/Mark)\ **Post date:** [April 23, 2020, 1:45pm UTC](https://forum.generic-mapping-tools.org/t/proj4-work-with-grdproject-problem/394/8 "2020-04-23T13:45:31Z")
Thanks a lot，Joaquim！ ---
**Author:** ![Mark](https://avatars.discourse-cdn.com/v4/letter/m/e9c0ed/32.png) [@Mark](https://forum.generic-mapping-tools.org/u/Mark)\ **Post date:** [April 23, 2020, 1:53pm UTC](https://forum.generic-mapping-tools.org/t/proj4-work-with-grdproject-problem/394/9 "2020-04-23T13:53:54Z")
and another question:[Why after grdblend ,the grid spacing changed?](https://flint.soest.hawaii.edu/t/why-after-grdblend-the-grid-spacing-changed/413) Hope help! Big Thanks!