Depth/height map of the world ? I mean public and free.

[Dr.Sid]

Hello there. Any of you know about of public domain (redistributable) height/depth map of the world ? In electronic form of course. I'm kinda doing my own subsim. Well in fact such map is not much important. Limited mission area with non-real custom maps would do too. But it would be great to have whole real world to explore.

The quality does not have to be any good. But I need something. And especially the copyright issues must be clean. I could grab height from google earth or both depth and height from some commercial atlas software, but that could cause me big troubles some day.

[Dr.Sid]

You see ? I tried the google again right after writing this post and look what I've found ..

http://www.ngdc.noaa.gov/mgg/fliers/01mgg04.html

2 minute resolution whole world. Perfect. So the question is .. do you know anything better ?

[Chock]

There's the stuff from the NASA space shuttle flight a few years ago, this is the data which several developers have used for improved terrain meshes in MS Flight Simulator. As far as I'm aware, the data is in the public domain (as is most NASA stuff like that). Most of it is in FSX and it crops up in products such as this http://www.justflight.com/product.asp?pid=40

Chock

[Dr.Sid]

Here is my fullres snapshot of Europe from Etopo:

[XabbaRus]

Looks good sid, as long as we have proper navigable seas, ie the Bosphorus and Panama Canal.

Like chock said the NASA stuff is public domain and hi res.

[Dr.Sid]

Looking looking and can't find it.

Etopo maps are too lowres for Bosphorus or Panama .. but such details could be painted manualy.

[Dr.Sid]

So I looked into DW. By the map you can see it uses abou 1km detail, which is later interpolated into let's guess 100m polygons.

Then I looked into DW file structure. I looked at the world file. And it has nice header mentioning gtopo30.
gtopo30+Google=http://edc.usgs.gov/products/elevation/gtopo30/gtopo30.html

Which means 1km resolution.

I will try to download it tomorrow.

[Letum]

Try googleing around for DEM maps.

Thats digital elevation data and in comes in *.dem files.

There are millions around, but for high quality ones you will need to pay.
Most are cheep.

If you chose low resolution, perhaps 30m, then your subsim will run faster and you will have more CPU for other features.

[Dr.Sid]

Ok .. found mentioned shuttle data, just a step from gtopo30. Gtopo30 looks quite OK, but it has no sea-depth. I would have to combine it with etopo, which I don't like at all.

http://eros.usgs.gov/products/elevation.html

[Zachstar]

For those wondering about this shuttle mission. The one that gave a public domain radar view of most of the earth.

http://en.wikipedia.org/wiki/SRTM
http://en.wikipedia.org/wiki/STS-99
http://srtm.usgs.gov/Mission/missionsummary.php
http://srtm.usgs.gov/Mission/quickfacts.php
http://www2.jpl.nasa.gov/srtm/

There are much higher resoultion missions involving unmanned spacecraft. However those sources are mostly private or military and not around for the general public.

A low resolution combination of SRTM height maps, Landsat data, and other sources (Night lights) can work well for a subsim with light flight aspects. Id say that a really good combination of data ought not to exceed 75-100 MB

[Zachstar]

A really wonderful source of data is NASA's Blue Marble series. Part of Visual Earth

http://earthobservatory.nasa.gov/Newsroom/BlueMarble/
http://earthobservatory.nasa.gov/New...monthlies.html
http://visibleearth.nasa.gov/
http://visibleearth.nasa.gov/view_se...ategoryID=2363


I love their City Light images.

http://visibleearth.nasa.gov/view_rec.php?id=1438

[Fish]

We should have a other then DTED 0, as we have now.

http://www.tec.army.mil/fact_sheet/DTED-HRTe.pdf

[Zachstar]

This image from Visible Earth is the needed bathymetry data. If SRTM developed data is without it for some reason.

http://visibleearth.nasa.gov/view_rec.php?id=8392

Combine it with SRTM data Version 2 for your earth surface. Then when you add in water. You simply set water to fill to sea level +- tidal effects and thats that for 3D.

For 2D I suggest you just use Blue marble maps (4 for the seasons)


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I have been digging around for info. I think this is where you can get the developed sets of SRTM data V2 (The data they came home with obviously has voids that needed to be filled over time)

NASA has released version 2 of the Shuttle Radar Topography Mission digital topographic data (also known as the "finished" version). Version 2 is the result of a substantial editing effort by the National Geospatial Intelligence Agency and exhibits well-defined water bodies and coastlines and the absence of spikes and wells (single pixel errors), although some areas of missing data ('voids') are still present. The Version 2 directory also contains the vector coastline mask derived by NGA during the editing, called the SRTM Water Body Data (SWBD), in ESRI Shapefile format.

ftp://e0srp01u.ecs.nasa.gov/srtm/version2/

Some info.

http://www2.jpl.nasa.gov/srtm/datatimeline.html

[XabbaRus]

Sid any luck?
Is 1km good enough resolution for Bosphorus and Panama canal?

[Zachstar]

Originally Posted by XabbaRus

Sid any luck?
Is 1km good enough resolution for Bosphorus and Panama canal?

You do not worry about those being on the "Big map" you let the program cut the area out and use an overlay that is of much better detail.

In that way you have a nice and detailed canal and not a 2GB download just for super detailed planetwide coverage that few will use in a subsim.

So you have one BIG tile and smaller detailed tiles.