# Q&A **URL:** https://forum.generic-mapping-tools.org/c/questions/5.md [Latest](https://forum.generic-mapping-tools.org/latest.md) · [Categories](https://forum.generic-mapping-tools.org/categories.md) · [Tags](https://forum.generic-mapping-tools.org/tags.md) --- ## [About the Q&A category](https://forum.generic-mapping-tools.org/t/about-the-q-a-category/21)
**Author:** [@leouieda](https://forum.generic-mapping-tools.org/u/leouieda)\ **Replies:** 18\ **Last updated:** [November 2, 2020, 9:05am UTC](https://forum.generic-mapping-tools.org/t/about-the-q-a-category/21 "2020-11-02T09:05:35Z")
This is a place to ask questions about using GMT and affiliated packages. If your question is about an affiliated package like GMT.jl or PyGMT, please apply the appropriate tag so we can better find and answer your ques… --- ## [Region specification without leading zero leads to crash](https://forum.generic-mapping-tools.org/t/region-specification-without-leading-zero-leads-to-crash/6497)
**Author:** [@thwbecker](https://forum.generic-mapping-tools.org/u/thwbecker)\ **Replies:** 3\ **Last updated:** [October 1, 2026, 7:55pm UTC](https://forum.generic-mapping-tools.org/t/region-specification-without-leading-zero-leads-to-crash/6497 "2026-10-01T19:55:01Z")
Hi when specifying a region as a float without leading zero, the parser will fail, e.g. as below. (github version). This is probably an uncommon use case, and not a high priority concern, but might be nice to have a mo… --- ## [Equal Earth projection](https://forum.generic-mapping-tools.org/t/equal-earth-projection/6489)
**Author:** [@darekk](https://forum.generic-mapping-tools.org/u/darekk)\ **Replies:** 16\ **Last updated:** [September 28, 2026, 11:19am UTC](https://forum.generic-mapping-tools.org/t/equal-earth-projection/6489 "2026-09-28T11:19:57Z")
Is it possible to apply the Equal Earth projection (=EPSG8857 to 9?) in GMT ? Thank You. --- ## [GMTCLibNotFoundError](https://forum.generic-mapping-tools.org/t/gmtclibnotfounderror/4545)
**Author:** [@muscovite](https://forum.generic-mapping-tools.org/u/muscovite)\ **Replies:** 4\ **Last updated:** [September 26, 2026, 1:53pm UTC](https://forum.generic-mapping-tools.org/t/gmtclibnotfounderror/4545 "2026-09-26T13:53:09Z")
Hello, i’m beginner user in GMT. I’ve installed GMT and pygmt (using pip and it’s suscess). But when I test it in notebook with the code : and the output is : anyone here can help me to fix this problem? Thanks i… --- ## [GMT plotting problem with geographic coordinates](https://forum.generic-mapping-tools.org/t/gmt-plotting-problem-with-geographic-coordinates/6482)
**Author:** [@Elmas](https://forum.generic-mapping-tools.org/u/Elmas)\ **Replies:** 8\ **Last updated:** [September 4, 2026, 10:28am UTC](https://forum.generic-mapping-tools.org/t/gmt-plotting-problem-with-geographic-coordinates/6482 "2026-09-04T10:28:05Z")
Hi everyone, I am experiencing a strange problem when plotting a small area with GMT using the Mercator projection (-JM). The region I specify is: -R38.7497222222/38.7661111111/9.00805555556/9.02444444444 However, the… --- ## [Question about sphdistance](https://forum.generic-mapping-tools.org/t/question-about-sphdistance/1096)
**Author:** [@szahirovic](https://forum.generic-mapping-tools.org/u/szahirovic)\ **Replies:** 4\ **Last updated:** [August 29, 2026, 11:18pm UTC](https://forum.generic-mapping-tools.org/t/question-about-sphdistance/1096 "2026-08-29T23:18:53Z")
Hi wonderful GMT team! Hope you are all doing well, despite the obvious challenges of 2020. I am trying to make distance grids using sphdistance. I am feeding it reconstructed mid-oceanic ridge line geometries (densifi… --- ## [Plot a schmidt stereonet](https://forum.generic-mapping-tools.org/t/plot-a-schmidt-stereonet/6067)
**Author:** [@Rom1](https://forum.generic-mapping-tools.org/u/Rom1)\ **Replies:** 20\ **Last updated:** [August 27, 2026, 2:40pm UTC](https://forum.generic-mapping-tools.org/t/plot-a-schmidt-stereonet/6067 "2026-08-27T14:40:39Z")
Hi everyone, I have a 2-column file containing azimuth and plunge values, representing the poles to fault planes. I would like to plot them on a Schmidt stereonet (equal-area projection), but I can’t get it to work — th… --- ## [Finding suitable colors for my map](https://forum.generic-mapping-tools.org/t/finding-suitable-colors-for-my-map/6481)
**Author:** [@aastha](https://forum.generic-mapping-tools.org/u/aastha)\ **Replies:** 2\ **Last updated:** [August 20, 2026, 4:52pm UTC](https://forum.generic-mapping-tools.org/t/finding-suitable-colors-for-my-map/6481 "2026-08-20T16:52:35Z")
HI everyone. I am using gmt 6.5.0 in linux, and i am having trouble finding suitable colors for my map. I have attached a scheenshot, and it just looks off. Anyone can help me please? I dont want white on the tibetan gro… --- ## [How to calculate the mantle Bouguer anomaly (MBA) and residual mantle Bouguer anomaly (RMBA)](https://forum.generic-mapping-tools.org/t/how-to-calculate-the-mantle-bouguer-anomaly-mba-and-residual-mantle-bouguer-anomaly-rmba/131)
**Author:** [@ghomsi123](https://forum.generic-mapping-tools.org/u/ghomsi123)\ **Replies:** 2\ **Last updated:** [August 7, 2026, 7:10pm UTC](https://forum.generic-mapping-tools.org/t/how-to-calculate-the-mantle-bouguer-anomaly-mba-and-residual-mantle-bouguer-anomaly-rmba/131 "2026-08-07T19:10:28Z")
Hi, Currently, I am using an ASCII grid and I would like to calculate the MBA and RMBA. Since I am working on the land (continent), it is necessary to use the bathymetry to compute the effect of the water or should I u… --- ## [Multiple colorbars changes the annotation fontsize](https://forum.generic-mapping-tools.org/t/multiple-colorbars-changes-the-annotation-fontsize/4945)
**Author:** [@JonathonLeonard](https://forum.generic-mapping-tools.org/u/JonathonLeonard)\ **Replies:** 18\ **Last updated:** [August 2, 2026, 10:39am UTC](https://forum.generic-mapping-tools.org/t/multiple-colorbars-changes-the-annotation-fontsize/4945 "2026-08-02T10:39:01Z")
Hi I’m plotting multiple colorbars side-by-side with different widths, and having trouble where the annotation size seems to scale with the colorbar width. I’ve done a lot of googling and a lot of trial and error and ca… --- ## [Psscale (colorbar) and its label font size](https://forum.generic-mapping-tools.org/t/psscale-colorbar-and-its-label-font-size/6472)
**Author:** [@carlosfherrera](https://forum.generic-mapping-tools.org/u/carlosfherrera)\ **Replies:** 8\ **Last updated:** [July 31, 2026, 6:07pm UTC](https://forum.generic-mapping-tools.org/t/psscale-colorbar-and-its-label-font-size/6472 "2026-07-31T18:07:12Z")
Dear community, I’ve been using GMT for several years and recently updated to GMT 6.6.0. In this version I noticed that the font size of the color bar labels change depending on the color bar length. For example: The sh… --- ## [Unstructured grid plots](https://forum.generic-mapping-tools.org/t/unstructured-grid-plots/6469)
**Author:** [@Secchi](https://forum.generic-mapping-tools.org/u/Secchi)\ **Replies:** 1\ **Last updated:** [July 22, 2026, 9:58am UTC](https://forum.generic-mapping-tools.org/t/unstructured-grid-plots/6469 "2026-07-22T09:58:22Z")
Dear community members, Anyone has some have solved a way to plot unstructured grids in pygmt? I need to workout in something faster for animations and nice color interpolation among the elements. I couldn’t find some… --- ## [Lambert projection with region of interest](https://forum.generic-mapping-tools.org/t/lambert-projection-with-region-of-interest/6470)
**Author:** [@montesi](https://forum.generic-mapping-tools.org/u/montesi)\ **Replies:** 1\ **Last updated:** [July 21, 2026, 9:46pm UTC](https://forum.generic-mapping-tools.org/t/lambert-projection-with-region-of-interest/6470 "2026-07-21T21:46:23Z")
I’m trying to make a equal-area map over a few ROIs with minimal local distortion. It looks like Lambert azimuthal should work, but the result always shows the entire globe, not just the ROI. Here’s an example taken from… --- ## [Cannot import name 'Axis' from 'pygmt.params'](https://forum.generic-mapping-tools.org/t/cannot-import-name-axis-from-pygmt-params/6443)
**Author:** [@jeromechine](https://forum.generic-mapping-tools.org/u/jeromechine)\ **Replies:** 4\ **Last updated:** [July 20, 2026, 10:43pm UTC](https://forum.generic-mapping-tools.org/t/cannot-import-name-axis-from-pygmt-params/6443 "2026-07-20T22:43:35Z")
Hi, I’m new to PyGMT. I’m trying to run these two lines: import pygmt from pygmt.params import Axis, Frame but I get the warning: ImportError: cannot import name 'Axis' from 'pygmt.params' (C:\\Users\\jerom\\anaconda3\\e… --- ## [How to cite PyGMT](https://forum.generic-mapping-tools.org/t/how-to-cite-pygmt/382)
**Author:** [@liamtoney](https://forum.generic-mapping-tools.org/u/liamtoney)\ **Replies:** 4\ **Last updated:** [July 16, 2026, 11:49pm UTC](https://forum.generic-mapping-tools.org/t/how-to-cite-pygmt/382 "2026-07-16T23:49:11Z")
I used PyGMT to create some figures on a manuscript. I’d like to cite PyGMT (along with GMT, which was also used stand-alone). What should I cite? @leouieda I see you’ve got a few talks/posters. Aside: With open-source … --- ## [Centering annotations on discrete colorbar bins](https://forum.generic-mapping-tools.org/t/centering-annotations-on-discrete-colorbar-bins/6457)
**Author:** [@henriws](https://forum.generic-mapping-tools.org/u/henriws)\ **Replies:** 4\ **Last updated:** [July 9, 2026, 8:09am UTC](https://forum.generic-mapping-tools.org/t/centering-annotations-on-discrete-colorbar-bins/6457 "2026-07-09T08:09:24Z")
Version: GMT 6.6.0 OS: Ubuntu Linux Hello everyone, I am trying to create a discrete horizontal colourbar where the numerical annotations sit centrally beneath each colour bin rather than at the bin edges. Currently,… --- ## [Help grdflexure](https://forum.generic-mapping-tools.org/t/help-grdflexure/6442)
**Author:** [@MariaG](https://forum.generic-mapping-tools.org/u/MariaG)\ **Replies:** 1\ **Last updated:** [June 9, 2026, 3:46pm UTC](https://forum.generic-mapping-tools.org/t/help-grdflexure/6442 "2026-06-09T15:46:49Z")
Hello everyone, I’m trying to model the flexure of the Juan Fernández Ridge using the GMT command grdflexure. Specifically, I am working on a section between Alejandro Selkirk Island and Robinson Crusoe Island. However… --- ## [Bug with psconvert? gmt begin \ png fails, but gmt begin \ png,ps works](https://forum.generic-mapping-tools.org/t/bug-with-psconvert-gmt-begin-name-png-fails-but-gmt-begin-name-png-ps-works/6423)
**Author:** [@Esteban82](https://forum.generic-mapping-tools.org/u/Esteban82)\ **Replies:** 5\ **Last updated:** [June 8, 2026, 9:40pm UTC](https://forum.generic-mapping-tools.org/t/bug-with-psconvert-gmt-begin-name-png-fails-but-gmt-begin-name-png-ps-works/6423 "2026-06-08T21:40:27Z")
Hi, I recently reinstalled my operating system (Kubuntu 26.04) and noticed a strange issue with GMT. The following script works as expected: gmt begin 3 png,ps gmt basemap -R0/1/0/1 -Baf gmt end However, if I rem… --- ## [Grdcont](https://forum.generic-mapping-tools.org/t/grdcont/6422)
**Author:** [@bleibi](https://forum.generic-mapping-tools.org/u/bleibi)\ **Replies:** 2\ **Last updated:** [June 6, 2026, 3:30pm UTC](https://forum.generic-mapping-tools.org/t/grdcont/6422 "2026-06-06T15:30:38Z")
3504250.tif (4.0 MB) My script loops over a number of geotiffs. Some are fully within the specified region, some partially, some are outside. Usually, grdimage and grdcont handle that correctly, but one tile with partia… --- ## [Gmt.conf not read in classic mode?](https://forum.generic-mapping-tools.org/t/gmt-conf-not-read-in-classic-mode/6419)
**Author:** [@thwbecker](https://forum.generic-mapping-tools.org/u/thwbecker)\ **Replies:** 16\ **Last updated:** [May 17, 2026, 11:43pm UTC](https://forum.generic-mapping-tools.org/t/gmt-conf-not-read-in-classic-mode/6419 "2026-05-17T23:43:36Z")
Sorry if this is a stupid question, but I cannot figure out why GMT classic mode (github compile) does not recognized my FONT modifications to the gmt.conf file. I’ve double checked that there is no conflicting gmt.conf … --- ## [Is there a simple replacement for the old GMT4 "psxy -m" option?](https://forum.generic-mapping-tools.org/t/is-there-a-simple-replacement-for-the-old-gmt4-psxy-m-option/6418)
**Author:** [@FionaDarbyshire](https://forum.generic-mapping-tools.org/u/FionaDarbyshire)\ **Replies:** 2\ **Last updated:** [May 15, 2026, 7:26pm UTC](https://forum.generic-mapping-tools.org/t/is-there-a-simple-replacement-for-the-old-gmt4-psxy-m-option/6418 "2026-05-15T19:26:41Z")
Hello, I’m updating some old GMT code to GMT6. The old GMT4 version was simple: with the psxy -m option one could plot from a location file broken into segments separated by “\>” characters, such as drawing lines between… --- ## [Plotting shaded spheres](https://forum.generic-mapping-tools.org/t/plotting-shaded-spheres/6412)
**Author:** [@Faris\_hamza](https://forum.generic-mapping-tools.org/u/Faris_hamza)\ **Replies:** 2\ **Last updated:** [April 21, 2026, 5:14pm UTC](https://forum.generic-mapping-tools.org/t/plotting-shaded-spheres/6412 "2026-04-21T17:14:45Z")
Hi, How can I plot spheres with shaded colors, giving it a shadow effect on a 2D map. --- ## [Creating a local mirror of datasets](https://forum.generic-mapping-tools.org/t/creating-a-local-mirror-of-datasets/6405)
**Author:** [@Andreas](https://forum.generic-mapping-tools.org/u/Andreas)\ **Replies:** 5\ **Last updated:** [April 21, 2026, 1:03pm UTC](https://forum.generic-mapping-tools.org/t/creating-a-local-mirror-of-datasets/6405 "2026-04-21T13:03:36Z")
The GMT website (Becoming a GMT mirror) gives a command for syncing/downloading the entire collection of datasets: rsync -av --delete rsync://oceania.generic-mapping-tools.org/gmtdata /your/local/gmtdata Say I did this… --- ## [Change default grid format from NetCDF to GeoTIFF](https://forum.generic-mapping-tools.org/t/change-default-grid-format-from-netcdf-to-geotiff/6404)
**Author:** [@Andreas](https://forum.generic-mapping-tools.org/u/Andreas)\ **Replies:** 8\ **Last updated:** [April 21, 2026, 10:28am UTC](https://forum.generic-mapping-tools.org/t/change-default-grid-format-from-netcdf-to-geotiff/6404 "2026-04-21T10:28:44Z")
NetCDF is the default grid format produced by GMT, but is there any way to change this? I would like GMT always to create GeoTIFFs; not NetCDF. I.e., it would be great if I don’t need to specify =gdal:GTiff every time. … --- ## [How to reuse the remote data set machinery for local data sets?](https://forum.generic-mapping-tools.org/t/how-to-reuse-the-remote-data-set-machinery-for-local-data-sets/3471)
**Author:** [@Esteban82](https://forum.generic-mapping-tools.org/u/Esteban82)\ **Replies:** 7\ **Last updated:** [April 21, 2026, 7:13am UTC](https://forum.generic-mapping-tools.org/t/how-to-reuse-the-remote-data-set-machinery-for-local-data-sets/3471 "2026-04-21T07:13:46Z")
I think that the remote data set are great, in particular because they are donwsample and it is possible to let GMT select the resolution needed for each map. However, some datasets won’t go to the server (due to lack o… --- ## [Problem with psconvert on pyGMT](https://forum.generic-mapping-tools.org/t/problem-with-psconvert-on-pygmt/2046)
**Author:** [@Feva67](https://forum.generic-mapping-tools.org/u/Feva67)\ **Replies:** 48\ **Last updated:** [April 16, 2026, 3:13pm UTC](https://forum.generic-mapping-tools.org/t/problem-with-psconvert-on-pygmt/2046 "2026-04-16T15:13:20Z")
Hey there, I’m trying to get pygmt to run on my pc, either through a Jupyter notebook or python command prompt, but had the same problem both times. It’s something to do with a psconvert error, but I have no idea how to … --- ## [Question about CPT unit modifier (+U\)](https://forum.generic-mapping-tools.org/t/question-about-cpt-unit-modifier-u-unit/6383)
**Author:** [@tllc46](https://forum.generic-mapping-tools.org/u/tllc46)\ **Replies:** 17\ **Last updated:** [April 15, 2026, 4:33pm UTC](https://forum.generic-mapping-tools.org/t/question-about-cpt-unit-modifier-u-unit/6383 "2026-04-15T16:33:23Z")
Hello GMT developers and users, I have a question regarding the unit modifier for Color Palette Tables (CPT). For reference, I am using Ubuntu 24.04 LTS and GMT 6.5.0, installed via apt. First, please consider the foll… --- ## [\-do options in plot or barb](https://forum.generic-mapping-tools.org/t/do-options-in-plot-or-barb/6400)
**Author:** [@PlanetGus](https://forum.generic-mapping-tools.org/u/PlanetGus)\ **Replies:** 0\ **Last updated:** [April 14, 2026, 12:09pm UTC](https://forum.generic-mapping-tools.org/t/do-options-in-plot-or-barb/6400 "2026-04-14T12:09:41Z")
Hi there, Quick question for the dev team: Any particular reason not to include -do (to replace NaNs with value) in plot ? -di is accepted though… Thanks, Guillaume --- ## [Using a color map on arrow plotting](https://forum.generic-mapping-tools.org/t/using-a-color-map-on-arrow-plotting/6395)
**Author:** [@Feva67](https://forum.generic-mapping-tools.org/u/Feva67)\ **Replies:** 3\ **Last updated:** [April 10, 2026, 2:43pm UTC](https://forum.generic-mapping-tools.org/t/using-a-color-map-on-arrow-plotting/6395 "2026-04-10T14:43:10Z")
Hello, I have been trying to make a pygmt plot with colored arrows according to length. I have tried adding cmap=True, fill=length to my plot call, but the function is not interpreting it as I expected and the arrows com… --- ## [GAMIT/GLOBK No Postfit and No Prefit](https://forum.generic-mapping-tools.org/t/gamit-globk-no-postfit-and-no-prefit/6396)
**Author:** [@dinarh10](https://forum.generic-mapping-tools.org/u/dinarh10)\ **Replies:** 1\ **Last updated:** [April 10, 2026, 12:07pm UTC](https://forum.generic-mapping-tools.org/t/gamit-globk-no-postfit-and-no-prefit/6396 "2026-04-10T12:07:37Z")
I am processing GNSS data using GAMIT/GLOBK 10.7 and encountered an issue with older datasets. Processing setup: Year: 2009, DOY 001 GAMIT/GLOBK: 10.7 Command: sh\_gamit -expt \ -d 2009 001 -orb… [Next page](https://forum.generic-mapping-tools.org/c/questions/5.md?page=1)