Best way to get 10 gores from a high res map?

[WilliamLear]

I have seen all the posts about this, but I can’t really find what I am looking for (for this project). I want to make a map with 10 gores from a large equirectangular map.

For this project I use this image: http://naturalearth.springercarto.co...clouds_16k.jpg (16200x8100)
I need a program that can handle large images and can keep the high resolution (very important).

From what I found Netpbm looks like the best option.
If this is true I have another question: How can I get this to work on windows. This kind of program is completely new for me and there are not a lot instructions on how to install that I can find on google or this forum. I used the link from this post (https://www.cartographersguild.com/s...l=1#post275897) to download Netpbm and used the Netpbm user manual, but I can’t get it to work.

I'm new to this forum so if I did something wrong please tell me.

[johnvanvliet]

it depends

easy and to really correct ?
or
a bit harder and correct ?

see my post here
#4
https://www.cartographersguild.com/s...ad.php?t=36936

[Redrobes]

Hi William,

I have made a new post to address your issue. I have checked it with your link image and it seems to work fine. If you could try it and let me know how well that worked out for you.

Please see:
https://www.cartographersguild.com/s...ad.php?t=37152


Below is small 5% version of your image.

[waldronate]

But, but, but...

What about offset gores to simplify assembly ( http://www.progonos.com/furuti/MapPr...ic-s75-i12.png )?

What projection are you using? Can you get bleeds to allow for overlap? ( https://www.mapthematics.com/Downloads/Gores.pdf )

How about polar rosettes of gores ( http://jcb.lunaimaging.com/media/Siz...n/02234002.jpg )?

What scaling do I need to print at to get this to fit on a globe of various sizes?

OK, I'll stop now.

[johnvanvliet]

if you use gdal or qgis ( uses gdal) and proj4 the overlap will be easy

Just a bit time consuming

see the second part of
https://www.cartographersguild.com/s...l=1#post330346




as for a rose
as in these maps
https://astrogeology.usgs.gov/search...ars_mola_globe
https://astrogeology.usgs.gov/search..._form&v1=Globe

some custom code was used , i think it is still someplace on the net

[waldronate]

Oh, OK. Thanks.

[WilliamLear]

Thanks a lot for the replies.

I want the best result, a bit more time consuming is not a problem
Your program works great Redrobes. Fast, simple and the result looks good.

I will check gdal and qdis later this week when I have time.

[Redrobes]

Thanks. I think Waldronate has indeed highlighted some short comings of it though. I did only do the sinusoidal with parallel lattitudes (in Y direction) staying parallel which is probably not ideal. And no overlap to make life easier. I will have to give it some more thought and may have to issue another update some time in the future.

[johnvanvliet]

the nteppm code is here
a small 5.2 KiB file
https://sourceforge.net/p/netpbm/cod...lty/ppmglobe.c

cutting a chunk of a simple cylindrical map , setting the center to 0 lat/ 0 long and transforming it to a transverse Mercator will work the best