Where to get height maps (real geo information)

[amigoface]

Hi beauty,

for now i have to do some experiments with all the suggestions a had in this forum
and keep you informed

in the meantime i have a little question :
you say that i have to know the lowest and higfhest altitude for the heightmap :

since i have splited the original height into many pages to use the terrain paging mechanism
have i to do this operation for all single page or for the whole heightmap ?


anyway thanks a lot !

[Beauty]

I have now experience with paged terrain and it depends to the used paging system.
Nevertheless I'm nearly shure that the highest and lowest points are related to the whole map.

In other words:
You define the height values for full black and full white.
Then (later by the terrain system) the height value of each grey pixels of the height map will be calculated by the black/white values.

By the way - do you still have a height map or do you have to create it geo information.
In second case you have to decide which height levels you map to black (lowest) and white (highest) colour.

After loading the terrain successfully you also should keep in mind that you possibly have to use more than one coordinate systems. (As I mentioned some posts ago.)

I hope you understand what I mean. My descriptions are not much formulated out.If you have further questions, just ask.

Thanks for keeping us informed. I'm interested in your results.

[amigoface]

Hi beauty,

since you use real world terrain data,
can you tell please what do you use as input/output data format
and what tool have you used to convert to ogre format ?


i have some issues to convert from srtm(Int16) to a format that the ogre terrain can understand

i only succeced to convert to 8bits png using gdal but it look horrible !

any help is welcome

[Beauty]

I don't remember the source file format. I just know it contained several numbers in plain text.
I think I converted it with gdal.
Also I made some calculations/corrections by a text editor.

In the past I had problems with height map images which were created by one or two image applications. (Irfanview?? Paint.NET??) I suppose there were problems (bugs?) with some internal settings in the image file header.
My solution was to use Photoshop, switch to the image to 16-bit mode (per channel) and saved the image in PNG or JPG format.

Only one time I imported real geo data about 2 years ago. It was a stony way and tooked much time. Now it could be faster (with all the notes and links of this topic), but still stony. Sorry for my bad memory.

[amigoface]

testing something ....

i will keep you informed

[Deathwish]

Oy guys, lots of usefull info on this thread !

Just a question from me, I've been working on a pet project of mine regarding heightmaps,
now it is easy enough to find heightmaps of areas, but I would like to have heightmaps of cities (not elevation of the city terrain, but the city buildings itself)

I've been doing this on smaller scale examples by making my own heightmap manually, however this is unacceptable if I am to work with a map of an entire city,
any ideas?

[Kojack]

Nokia's http://here.com mapping site has detailed height maps of some cities (in australia they have sydney and melbourne, not brisbane where I am). It's only viewable as part of their 3d map viewer thing, you can't just download them.
But I'm sure there'd be a way to extract the height map data, in the same way that people found out how to leach maps from google (there's an X-Plane plugin that when activated it found your plane's current world coordinates, downloaded a heap of google maps around that location and rebuilt the world terrain files to use them instead of the default data).
Of course that's against the eulas and stuff, so it's naughty and you shouldn't do it.

Apple maps seem to use the same 3d source as Nokia's one (aerial lidar). Although Nokia are also currently travelling around making lidar scanned 3d point cloud maps from road level, I can't wait to give that a try!

Edit: Turns out the nokia viewer is written in javascript and webgl, so it's already been reversed engineered and people have loaded it's heightmaps into blender and sketchup. http://idiocode.com/2012/02/01/nokia-3d-map-tiles/

[Deathwish]

Great news, thanks a lot, will give this a try. I too need to use this in blender
Well my idea is definitely not to break some EULAs ;D