Post Reply 

Merge map sections

Nov 4, 2012, 14:57
Post: #1
Merge map sections
I've downloaded some texture maps of Earth and Mars that consist of a number of JPG images that are all 1024 pixels square. What I want to do, and I've tried and failed so far, is to combine the separate images to make one big map of the planet surfaces. I assume this will be possible by tiling the images.
I've had a google around but can't find any tutorials related to combining sections of a map together.
Any thoughts, hints or pointers in the right direction appreciated.

[Image: DjIVv.png?1]

My DeviantArt gallery
http://caz747.deviantart.com/
Find all posts by this user
Quote this message in a reply
Nov 4, 2012, 15:13
Post: #2
RE: Merge map sections
I suggest you have a look at the various types of map projections: http://en.wikipedia.org/wiki/Map_projection to start with.

Also, how do you know which image relates to which part of the sphere?

Kevin
Find all posts by this user
Quote this message in a reply
Nov 4, 2012, 16:06
Post: #3
RE: Merge map sections
@caz

Maybe a bit more information required

How many tiles will there be in each row and how many rows will make up the entire image?
Is there much (or any) overlap between images?

If not too many tiles in a row, then look at assembling all the rows into images, rotating 90 deg and assembling these into the complete image.

You could use Gimp for this with the pandora script
http://registry.gimp.org/node/131

You might be better off, same procedure but using Hugin
http://hugin.sourceforge.net/

or there is an application for this (really info only) Nip2
http://www.vips.ecs.soton.ac.uk/index.php?title=Nip2
Not so easy to use. The best example of use I came across is this
http://gw.gamependium.com/tools/perfectmap/

** https://www.gimp-forum.net/ now answering questions**
Find all posts by this user
Quote this message in a reply
Nov 4, 2012, 17:21
Post: #4
RE: Merge map sections
Thanks for the quick reply guys.

Apologies for no quoted text but that feature still won't work.

First off, and I should've explained myself better, I'm not trying to make a map as such but a large picture of a planet surface that I can use as the base for one of my own planets.
The images that I downloaded have all the JPGs in different folders and each one is numbered so I guess that I'll be able to fit them together in the right sequence by following the numbers, but that is just a guess. If not then I'll have to rely on matching the natural features of the planet surface to find the right order. A bit haphazard but it's the best way I can think of.

There are about 200 separate pictures that make up the Mars map and I don't think there's any overlap between them - I've moved a few around and they seem to fit together quite well. Due to the amount of JPGs involved I am hoping to find a way to combine them that doesn't involve scaling each picture down and then positioning them by hand.

I think I will try Hugin as that sound like it might do the job, but in all honesty this is just one big experiment on my part and I have no real idea what I'm doing. Still there's only one way to learn.

Thanks for the links and info, I'll report back on how good or bad things turn out.

[Image: DjIVv.png?1]

My DeviantArt gallery
http://caz747.deviantart.com/
Find all posts by this user
Quote this message in a reply
Nov 4, 2012, 18:53
Post: #5
RE: Merge map sections
200+ images might be an image 15 tiles x 15 tiles and if each tile is 1024 pix square that is a big image. That was what nip2 was made for.

I would forget pandora, Hugin works best with overlaps.

Perhaps have a look at making strips with the Imagemagick (command line) 'montage' command

Have to confess, I am more than a bit flakey with that command.

** https://www.gimp-forum.net/ now answering questions**
Find all posts by this user
Quote this message in a reply
Nov 5, 2012, 18:31
Post: #6
RE: Merge map sections
It turned out to be a massive image, the print size of the finished image is 2.9 metres by 1.4. It's no wonder my old PC was blowing hard when I was putting the different sections of the picture together. At one point the file size was 1.3 GBs, Gimp did flash up some warnings about that as did windows manager.

I tried Hugin but it couldn't find any control points and I don't know enough about how it works - just had a quick look through - so it was a bit of a non starter. I'll have a good look at it later as it seems like it will be a handy programme to have.
Then I tried Pandora and had no luck with that as the images kept disappearing but it did have the answer in another way. I opened all the images as layers - as Pandora suggested - with a background layer 10,000 pixels square and then after some head scratching was able to move each one so that they all lined up in the right order and then spent a couple of hours fine tuning their positions. And now I have one hell of a good picture of Mars' surface.

The finished Jpg is 10mb but 314mb in memory, not really sure who that one works?

Thanks for all the advice it help me to get the job done in my usual haphazard way.Cool

[Image: DjIVv.png?1]

My DeviantArt gallery
http://caz747.deviantart.com/
Find all posts by this user
Quote this message in a reply
Nov 5, 2012, 18:46
Post: #7
RE: Merge map sections
Well done using pandora, I would balk at anything that size. I quite like it for a simple panorama. Once did this as a demo for anyone interested.
http://www.youtube.com/watch?v=zBma6CT3mjY

File size
10000 x 10000 pix = 100000000 pix
each pix has 3 channels r g b
so that is 300000000 bytes divide by 1000 for kilobytes and again 1000 for megabytes = roughly 300 MB in memory. Can be bigger again with an alpha channel and once gimp starts saving for undo's, bigger again.

Just shows how much the jpg compression is.

** https://www.gimp-forum.net/ now answering questions**
Find all posts by this user
Quote this message in a reply
Nov 5, 2012, 18:58
Post: #8
RE: Merge map sections
I forgot to mention earlier, the picture of Mars I put together had 32 separate layers to it. The different folders that came with the download are for different resolution of the planet surface.The next one up as 140 layers so I think I'll keep away from that one, the old PC might self destruct with something that big.

[Image: DjIVv.png?1]

My DeviantArt gallery
http://caz747.deviantart.com/
Find all posts by this user
Quote this message in a reply
Post Reply 


Possibly Related Threads...
Thread: Author Replies: Views: Last Post
Exclamation Map to object crashed HELP!!!! Elite Warrior 12 436 Aug 21, 2014 19:02
Last Post: Elite Warrior
  Batch Merge Layer Group stigzler 15 740 Jul 5, 2014 13:04
Last Post: stigzler
Question Image Map Tool: No Image Displaying Softly 1 282 Apr 11, 2014 07:06
Last Post: ofnuts
  Map pixels of square to circle foxmuldr 5 612 Oct 11, 2013 03:53
Last Post: foxmuldr
  Is there a way to make an image map with copiable text for a website? Elysium 2 490 Jan 5, 2013 01:15
Last Post: Elysium

Forum Jump:


GIMP ForumPortalArchiveContactTermsRSS