PDA

View Full Version : Converting map to normal map



Jelle_W
10-31-2013, 01:31 PM
- This problem was resolved! -

I want to convert a map from NASA (http://visibleearth.nasa.gov/view.php?id=73934) into a normal grayscale 8 bit heightmap.

On the source page it states:

We recommend using visualization software to view the file. Although it is possible to import the file into Photshop CS and later, Photoshop will not read the signed data correctly: elevation values above sea level start at 0, while negative elevations "wrap" to values near white (65535), which is sea-level.

I looked around assuming that more people have tried converting this particular map, and i was right, however the one tutorial that i do understand (http://poniesandlight.co.uk/notes/creating_normal_maps_from_nasa_depth_data/) halfway through needs you to download a MAC OSX script and i have no MAC.

In said tutorial there is some additional information on the file format, though to me it could be just aswell chinese characters.

I've also search google using broader terms but i wasn't able to find tutorials on how to achieve the end result i want as far as i can tell. So if someone could put me on the right track that would be great. I have Photoshop CS5 incase that's helpfull information.

- This problem was resolved! -

Midgardsormr
11-01-2013, 01:41 PM
First, do you really want an 8-bit heightmap of the entire world? If you reduce it to only 256 levels, there won't be enough detail left in it to make it worthwhile.

And do you really want a normal map (the purple image at the bottom of the screen)? Or do you want to stop at the point where you have the heightmap? The tutorial's Mac-only instructions start right after the heightmap's been prepared. If you continue, you'll wind up with the normals. If you instead stop in step 3 and go to Image > Mode > 8 bits/Channel and Image > Mode > Grayscale, you should have what you want. If you're not running the script to make the normals, you don't necessarily need to resize, either. Seems to me that doing so misses the point of getting this enormous file to begin with—why download such a huge image if you're just going to throw away 96% of the pixels?

Jelle_W
11-01-2013, 05:24 PM
First, do you really want an 8-bit heightmap of the entire world? If you reduce it to only 256 levels, there won't be enough detail left in it to make it worthwhile.
Yes



And do you really want a normal map (the purple image at the bottom of the screen)? Or do you want to stop at the point where you have the heightmap? The tutorial's Mac-only instructions start right after the heightmap's been prepared. If you continue, you'll wind up with the normals. If you instead stop in step 3 and go to Image > Mode > 8 bits/Channel and Image > Mode > Grayscale, you should have what you want. If you're not running the script to make the normals, you don't necessarily need to resize, either.

just a few hours earlier i had an e-mail exchange with the writer of the tutorial, and he said something similar.


Seems to me that doing so misses the point of getting this enormous file to begin with—why download such a huge image if you're just going to throw away 96% of the pixels?

I want to use the map of the earth in a particular program which will only take 8 bit grayscale heightmaps, so i'm sure i want this. And the dimensions which i want to use are greater then any of the smaller resolution images. I rather downscale to preserve what little extra detail that might still show as upscale a map.

I'm looking at the 8bit grayscale heightmap right now :) my problem is resolved :)