Digital map to .png or .jpg or .gif

[Jelle_W]

Hello everyone,

I've been trying software and waiting for maps to download and i can't come to the end result i want so that's why i'm making this topic.
I want to use the ETOPO1 format ice-surface map from http://www.ngdc.noaa.gov/mgg/global/global.html as a greyscale heightmap. I have downloaded and tried GEODAS and was able to get a blue shade map of the world but i can't export it as an image in it screencapture won't work because the map is a way bigger resolution as my screen supports. And scaling it up afterwards would get quircky.

An other solution would be to somehow merge the heightmap and bathymetric map from http://earthobservatory.nasa.gov/Fea..._monthlies.php but the color shades would mix up i guess but if it's possible i'm open to it. I don't expect it is but just to be sure.

So yeah, i basiclly am looking for a heightmap (as an image file, TIF?) of both under and above water terrain, with the ice cap on top of it for the poles in a size of atleast 21600*10800. I'm OK with downscaling. I'm willing to install freeware or trial software whatever. I'm just seriously annoyed at this point i couldn't figure it out after 5 hours of googling and trying stuff out that i have to bother you with the question

Kind regards,

Jelle

[Redrobes]

I think I can do this - gimme a couple hours...

[Jelle_W]

That would be seriously awesome. Thanks in advance for even trying!

[Redrobes]

Ok result time:

View this
http://www.viewing.ltd.uk/Temp/CG/Topo/Topo_Small.png

Download this cos its 320Mb
http://www.viewing.ltd.uk/Temp/CG/Topo/Topo.png

Once you have downloaded it then ill remove it as its a bit of a burden on the ole web site space.

It should be a 16bit PNG and should have values in accordance with the values in the DEM file inc the "no data" value. I dont have much to view this as a 16bit greyscale PNG (Photoshop should be ok tho) and I would have used an HF2 but it does have all the sub sea bathymetry included. In fact looking at Africa is notably & surprisingly flat in some regions. The plains I guess.

This seems to be the Amazonian basin.

If you get stuck with the 16bpp then you can use Image magick to convert it. I used it to get it from my raw grey format to the 16 bit greyscale PNG so it does work. Its also free and mighty useful. I used my own tool to decode the file on the site tho.

[Jelle_W]

i can see directly the andes and the sea next to it are nearly the same shade of color grey. This is impossible, i'm sorry to say but this won't work.

the edges of the rings are contrast with the supossedly higher area which lowers for a bit and poof it's high again. This wouldn't work. I appreciate the work, i really do, but this is not what i'm looking for, kind of bummed i have to say it.

But well, i need a solution for the problem and this isn't it so the topic isn't solved

srtm_ramp2.world.540x270.jpg

In the picture above the himalaya and andes are clearly visible white, this means they are very high, ever so slightly the colors turn to black indicating it's lower. But the sea is used as bottom in this heightmap and doesn't account for the ocean floor. In the ETOPO1 they are both in the same image, but i can't use the color scheme. I have to proces it with software which only takes greyshades heightmaps. -it's non optional i use this software-

so i'm sorry to say that image won't work. I really appreciate the work you've put in, unfortunattely it's not what i'm looking for. i'm sorry to say.

[Redrobes]

Yeah the image I have uploaded is 16bits and when you view it like the upload then every 256 shades and it reverts back around to black and climbs back to white again. I.e. my image is 256 times as accurate as your greyscale cos yours is in 8 bits. If you want to drop the height resolution then you can do that with image magick.

Its no problem. Now that I have it converted ill convert it some more to HF2 and generate the 8 bpp PNG file. If you have photoshop tho you might still want to grab that file cos it might look right in that.

[Redrobes]

Ok thats done. It will look like this. Its going to be 35Mb so gives you some idea of how much lower vertical height res its going to be. The new one is called Topo8.png in the same ftp dir. Just give it about 3 mins to get it up there.

[Jelle_W]

i guess seen the size it isn't 21600*10800 pixels as i requested. The problem is that 1 pixel in the original is 2KM, loosing 1 pixels is loosing 2km in height variation, when it comes to steap hills that is a lot.

Can i do the proces myself? i have photoshop. 8 bit is good enough.

[Redrobes]

Seriously... it is...

http://www.viewing.ltd.uk/Temp/CG/Topo/Topo8.png

[Jelle_W]

Wow. I must be even worse in file formats than i already thought. Awesome, thank you. I'm going to try it out and be sure to let you know how it worked out!