# Orthographic projection with no lines of Long/Lat

**URL:** <https://forum.generic-mapping-tools.org/t/orthographic-projection-with-no-lines-of-long-lat/6504>\
**Category:** Q&A\
**Created:** [October 24, 2026, 4:48pm UTC](https://forum.generic-mapping-tools.org/t/orthographic-projection-with-no-lines-of-long-lat/6504 "2026-10-24T16:48:41Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![PDA123](https://avatars.discourse-cdn.com/v4/letter/p/eb9ed0/32.png) [@PDA123](https://forum.generic-mapping-tools.org/u/PDA123)\
**Post date:** [October 24, 2026, 4:48pm UTC](https://forum.generic-mapping-tools.org/t/orthographic-projection-with-no-lines-of-long-lat/6504/1 "2026-10-24T16:48:42Z")

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I’m new to using GMT 6.40 and enjoy it very much.

In making an orthographic projection of the Earth I only want the equator presented on the result and no lines of longitude or latitude. How do I do it?

Here’s the code I use now;

gmt begin GMT\_tut\_5  
gmt set GMT\_THEME cookbook  
gmt coast -Rg -JG-045/10/6i -Bag -Dc -A5000 -Gwhite -SDarkTurquoise  
gmt end show

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**Author:** ![Esteban82](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/esteban82/32/54_2.png) [@Esteban82](https://forum.generic-mapping-tools.org/u/Esteban82)\
**Post date:** [October 24, 2026, 6:19pm UTC](https://forum.generic-mapping-tools.org/t/orthographic-projection-with-no-lines-of-long-lat/6504/2 "2026-10-24T18:19:58Z")

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Hi @PDA123. Welcome to the GMT forum.

`-Bag` draws the graticule. To keep only the equator, use latitude gridlines every 90° and no longitude lines:

```auto
gmt begin GMT_tut_5
    gmt set GMT_THEME cookbook
    gmt coast -Rg -JG-45/10/6i -Dc -A5000 -Gwhite -SDarkTurquoise -Byg90
gmt end show

```

Lines fall at -90°, 0° and 90°, and the poles are just points, so only the equator shows.

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<div class="post-metadata">

**Author:** ![PDA123](https://avatars.discourse-cdn.com/v4/letter/p/eb9ed0/32.png) [@PDA123](https://forum.generic-mapping-tools.org/u/PDA123)\
**Post date:** [October 24, 2026, 7:03pm UTC](https://forum.generic-mapping-tools.org/t/orthographic-projection-with-no-lines-of-long-lat/6504/3 "2026-10-24T19:03:03Z")

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> [@PDA123](#):
>
> -Bag

Thank you. That works very well.

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**Author:** ![nicholasjackson](https://avatars.discourse-cdn.com/v4/letter/n/ac91a4/32.png) [@nicholasjackson](https://forum.generic-mapping-tools.org/u/nicholasjackson)\
**Post date:** [November 7, 2026, 1:01am UTC](https://forum.generic-mapping-tools.org/t/orthographic-projection-with-no-lines-of-long-lat/6504/4 "2026-11-07T01:01:50Z")

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The -Byg90 approach makes sense for isolating the equator without drawing longitude lines. Since the longitude interval is omitted, only the latitude graticule is rendered, and the poles collapse to points in the orthographic projection, so the equator is all that remains visible. Good to know it worked for you, PDA123. This is a useful trick when you want a clean globe view without the full graticule cluttering the map.