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Where to get height maps (real geo information)

Posted: Sat Mar 07, 2009 4:00 am
by Beauty
Hi,

I would like to add terrain with properties of the real world.
For example my city with its mountains around.

On Google maps I can get textures, but I couldn't find height maps or similar geo data with which I could create it.

The google API offers the maptype terrain, but this only pseudo height information (physical relief map, e.g. here). Good for a human eye, but not usable for height maps.
Google has height information, because the application Google Earth can show terrain. So it gets this informations by internet connection. (I suppose this is no public API.)

I found many links about geo data and there are also free map archives on websites.
But I don't know how to use this data format.
Maybe somewhere there is a possebility to enter lat/long/zoom data and get back the related data.

Does anybody has an idea or experiences where to get the wanted data and how to create height maps?
Also it could help if somebody knows a special interest group forum where I can ask.

Maybe somehow it's possible to use Web Map Services?
http://en.wikipedia.org/wiki/Web_Map_Service
http://en.wikipedia.org/wiki/Open_Geospatial_Consortium

Re: Where to get height maps (real geo information)

Posted: Sat Mar 07, 2009 10:28 am
by PolyVox
I've been thinking for my own game that I'd like to use real world height data of countries so I have been researching this a little myself. One of the first stops should be NASA's 'Blue Marble Next Generation' project where you can find lot of satallite imagery (for all the months of the year) and heightmap data. Some links:

http://earthobservatory.nasa.gov/Features/BlueMarble/ - Main page
http://earthobservatory.nasa.gov/Featur ... thlies.php - Monthly images and heightmap data
http://earthobservatory.nasa.gov/Featur ... 0x2700.jpg - A low res heightmap

The heightmaps which are images are just 8-bits of precision (I think) which isn't really enough. But I did find some with 16 bits of precision in a custom file format which they told you how to open. But I can't find them again now :?

Also, this thread talks about extracting heightmaps from Google Earth. I haven't tried it yet though:

http://www.tt-forums.net/viewtopic.php?f=29&t=27052

Let me know if you find anything else useful...

Re: Where to get height maps (real geo information)

Posted: Sat Mar 07, 2009 10:33 am
by PolyVox
Ok, I found the high res one. It was part of the original Visible Earth, not Next Generation. You can see the details here:

http://visibleearth.nasa.gov/view_rec.php?id=8391

And the torrent file is here:

http://visibleearth.nasa.gov/view_detail.php?id=8391

Re: Where to get height maps (real geo information)

Posted: Sat Mar 07, 2009 12:20 pm
by reptor
3-meter intervals

http://www.wvgis.wvu.edu/data/dataset.php?ID=261

there are other datasets too at that website.

Re: Where to get height maps (real geo information)

Posted: Sat Mar 07, 2009 1:31 pm
by milliams
The one used by the OpenStreetMap project for the contour information is SRTM. There are occasional holes but these can be filled with some kind of spline interpolation.

Re: Where to get height maps (real geo information)

Posted: Mon Mar 09, 2009 11:11 am
by Beauty
Great links :)
I'll tell you about news, when I found more information or get some import experiences.

Re: Where to get height maps (real geo information)

Posted: Mon Mar 09, 2009 12:06 pm
by Beauty
On the CeBIT exhebition in Germany somebody told me, that contour lines are widespreaded in geography science and survey. There are free contour line maps available by the German Land Surveying Office (maybe also for other countries).
So it could be interesting, if there are converters for generation of height maps.

Here I found an algorithm how this could be done (based to triangle subdivision). Also interesting for creation of a Mesh.
http://www.geocities.com/powersof2000/P ... rain1.html

This is a list of height map software. I didn't discovered it yet, but it could be interesting:
http://wareseeker.com/free-height-maps

Also I found the open source geo converter GDAL, but I'm not shure, if it can create height maps:
http://en.wikipedia.org/wiki/GDAL

The GeoTIFF file format seems interesting for us (created by a NASA member):
http://www.remotesensing.org/geotiff/sp ... fhome.html
http://trac.osgeo.org/geotiff
GeoTIFF is a public domain metadata standard which allows georeferencing information to be embedded within a TIFF file. The potential additional information includes projections, coordinate systems, ellipsoids, datums, and everything else necessary to establish the exact spatial reference for the file. The GeoTIFF format is fully compliant with TIFF 6.0, so software incapable of reading and interpreting the specialized metadata will still be able to open a GeoTIFF file.

Thanks for the answers!
By the way - the forum thread about extracting heightmaps from Google Earth seems to be nice!

Well, these days I don't have much time, but I keep my eye on this theme

Re: Where to get height maps (real geo information)

Posted: Fri Mar 20, 2009 1:03 pm
by Beauty
I found a great page: Virtual Terrain Project
www.vterrain.org
The goal of VTP is to foster the creation of tools for easily constructing any part of the real world in interactive, 3D digital form.
It's free, open source and has a licence without restrictions.
Also: There is a huge link list for other terrain related software and pages that contains terrain data.
(e.g. an overview for Undersea Terrain Elevation (Bathymetry) )

---------------

A second interesting thing are the GeoTools.
http://docs.codehaus.org/display/GEOTOOLS/Home
GeoTools is an open source (LGPL) Java code library which provides standards compliant methods for the manipulation of geospatial data, for example to implement Geographic Information Systems (GIS). The GeoTools library implements Open Geospatial Consortium (OGC) specifications as they are developed, in close collaboration with the GeoAPI project.
Without a wrapper it can't be used by Ogre applications, but maybe this is useful to create a tool for hightmap generation. (Maybe there is still such a tool using this library?)

---------------

If somebody knows a good geo forum, just tell it. There I also can ask for suggestions or available applications for our target.
update for myself: geoclub.de (only German)

Re: Where to get height maps (real geo information)

Posted: Fri Mar 20, 2009 1:16 pm
by Beauty
By the way - 3 days ago the ESA send a satellite to space. The Gravity field and steady-state Ocean Circulation Explorer (GOCE) will survey the earth with high precision. Main target is the climate research, but the measured data also allowes to create precise height maps of the earth, including the ocean ground.

* Measure accuracy: 1-2 cm (for users of proprietary units - this means 0.4 .. 0.8 intch :lol: )
* Flight height: ~250 km (~155 miles)
* Speed: 29.000 km/h (18.000 mph)
* Circumnavigations: 16/day
* Ionic drive
* All in all there are many innovations in it

Official page:
http://www.esa.int/esaLP/LPgoce.html

Re: Where to get height maps (real geo information)

Posted: Fri Mar 20, 2009 4:26 pm
by Beauty
In Wikipedia is an overview of common geo data formats:
http://en.wikipedia.org/wiki/GIS_file_formats

Today a read an article in a German IT magazine:
The Symbology Encoding (part of the Styled Layer Descriptor) is a more and more common XML data format for visualisation of geo data (used by free and commercial tools). Unfortunately there is only less information in Wikipedia, but I wanted to tell it, because generally it could be useful to know this standard of the Open Geospatial Consortium (OGC).
http://en.wikipedia.org/wiki/Styled_Layer_Descriptor
http://www.opengeospatial.org/ogc
http://www.opengeospatial.org/standards/symbol

Re: Where to get height maps (real geo information)

Posted: Sun Mar 22, 2009 9:41 pm
by PolyVox
Wow, that's a lot of good links :) It certainly seems there is plenty of data out there if you serch for it!

Re: Where to get height maps (real geo information)

Posted: Wed Apr 01, 2009 7:43 am
by johnhpus
It may have already been mentioned somewhere in the flood of links, but if not, be sure to check out the USGS and their free online store of maps.

They seem to have almost everything you could want and extremely detailed at that -- seriously, down to bird migration ranges and hydrological regions.

Re: Where to get height maps (real geo information)

Posted: Wed Apr 01, 2009 11:13 am
by Beauty
Thanks for the tip.
There is many information, so I took a minute to find the right map section.

Here is the map type overview. As second step you have to order the wanted map.
http://egsc.usgs.gov/isb/pubs/booklets/ ... smaps.html

A great thing is the Map Locator. It's a Google Maps interface. There you go to the wanted area, set a marker and then you see which maps are available. Really great!
http://store.usgs.gov/b2c_usgs/usgs/map ... 4ROOT)/.do
Unfortunately there seems to be no detailed map of Germany :cry:

Also there I found an interesting thing in the forum:
Convert RRD / ADF format (ArcView) to TIFF using the software gdal.
http://isis.astrogeology.usgs.gov/IsisS ... php?t=1478

Re: Where to get height maps (real geo information)

Posted: Sat Apr 16, 2011 4:36 pm
by Beauty
The author of the Ogre game SimNation published an interesting hint:

There is a website with free GIS data (geo information). The project name is Natural Earth.
The downloadable database contains information like this:
world map, continents, countries, rivers, cities, height data, sea depth data, ...

Formats are:
* ESRI shapefile format (vektor format)
* TIFF format with a TFW world file
* coordinates based on WGS84

Website:
http://www.naturalearthdata.com

Downloads:
http://www.naturalearthdata.com/downloads

Re: Where to get height maps (real geo information)

Posted: Sat Apr 16, 2011 7:24 pm
by Beauty
Update for GIS data of the Natural Earth project: The developer of SimNation published his C++ code to load data.

Look to this forum topic: ESRI shapefile reader (only lines/polygons yet)
(If you tried the code, please give feedback in that thread and tell us how it works.)

Re: Where to get height maps (real geo information)

Posted: Sat Aug 27, 2011 12:30 am
by bigbman
Wow, an overwhelming amount of information here. What's the latest consensus? I have read about a manual method using Google Earth + Sketchup + 3DS to get a model... I'm looking for a more automated approach.

Re: Where to get height maps (real geo information)

Posted: Sat Aug 27, 2011 1:11 am
by Beauty
Nice to hear that you like the links. I found them on different places and thought, it's good for others to publish them here.

Two years ago I got height data of the wanted area (I suppose by a payed geo service) and I converted this to an other format by a command-line tool, perhaps gdal. This new format was a text file with many numbers. To convert it to an Ogre related height map I had to do calculations manually. (sorry, I don't remember details, but it was a stony way)
For testing purposed I grabbed a texture from Google maps. (I think it's not allowed to use it in other applications. Maybe only for payed content?)
Then it was difficult to adjust the texture to the heightmap terrain. I had no exact latitude/longitude coordinates.

Also I remember that some websites/databases had no data of Europe. Others had just low resolutions.


For the Ogre Procedural Geometry Library now exists a parser script for [url=http:/www.openstreetmap.org]OpenStreetMap[/url]. So partial/selected content can be re-created in Ogre applications.
Maybe it's also possible to modify the parser to import data from other sources, e.g. height information.
The parser script was published here. If I read right, now it was added to the "official" repository.


If you (or anybody else) has experience with import of geo information, feel free to give us a report.

Re: Where to get height maps (real geo information)

Posted: Tue Sep 20, 2011 11:09 am
by amigoface
hi,

i want to use ogre with real world data (srtm heightmap/satellite imagery)

has any one made similar things and can share some ideas, tips ?

Re: Where to get height maps (real geo information)

Posted: Tue Sep 20, 2011 8:26 pm
by Beauty
First step is to find the needed data (region and resolution).
There are free geo databases. Alternatively there are agencies where you can buy data (e.g. for higher resolutions).

Second step is to convert the data (somehow) for usage with Ogre.
There are differences between data formats and coordinate systems. Well, a complex topic. You should know what you need and look for GIS tools (GIS = Geo Information System) which fits your needs.

Third step is to get a texture and find the correct coordinates for "merging" height and texture data.


Very interesting could be the Ogre add-on Ogre Procedural. Somebody wrote a script for importing data from the OpenStreetMap database.
Alternatively there are extensions for the 3D modelling tool Blender which can import data from OpenStreetMap.

These are my spontaneous thoughts. I'm no specialist and have less experience with real geo data. Further suggestions are always welcome.

Re: Where to get height maps (real geo information)

Posted: Wed Sep 21, 2011 10:16 am
by amigoface
hi beauty ! :P ,

well i have already the heigtmap and texture corresponding to the same region :


the heightmap image is about 3000X3000 pixels approx
the satellite image is about 52000X26000 pixels approx (it's a quick bird image obtained at my work)

i am making a little flight sim project :
now suppose that i split the two images to get 52X26 parts so i have 1352 files for heightmap and imagery
now what are my options to design my level with these data plus other objects like airport/ surrounding buildings areas ... etc ?

i want to use ogitor as final level editor to place objects in the right positions
but i cannot load all the terrain pages in ogitor since i have a lot and it can take hours to get them in the editor :

is there a way to load the pages in a regular ogre app/ export the scene to dotscene file and the load that file in ogitor with all the 1352 terrain pages ,
after that i can edit the level by placing the various objects in the scene

Re: Where to get height maps (real geo information)

Posted: Wed Sep 21, 2011 11:35 am
by Beauty
To already have the data is a good starting point.

You also need to know, to which real dimension you want to map the texture and terrain data. (e.g. 30 x 30 km²)
This is important for converting to Ogre. In my application I use 1 Ogre unit for 1 meter. (If you use "proprietare" units like miles, you can do it, too.)
For importing the height map you also need to define the height values of black and white.
In the Terrain Scene Manager, black is related to Y=0 in Ogre coordinates. Dependent to your used coordinate system you could need to add a height offset or do more advanced coordinate calculations.
For a flight simulator it could be useful to use a coordinate system, which is common for airplanes. Then you can apply related flight calculations. If you do all calculations in Ogre coordinates you can't use common flight equations. Adopting equations to the Ogre coordinate system could be difficult. In my maritime applications I do the calculations in the North-East-Down coordinate system. Only for visualization I convert them to Ogre coordinates.
Just a little suggestion. :wink:

Why do you want to tile the map so much?
You could use 10 x 10 tiles which are related to 300 x 300 height map pixels (100 in total).
I only have experience with the Terrain Scene Manager. This always needs a squared terrain. (Length and width had to be equal.) Maybe this condition is the same for the new Ogre terrain component.
About the details for tiling and loading by Ogitor you should talk in the Ogitor forum topic. The people there know more practical aspects.

Re: Where to get height maps (real geo information)

Posted: Mon Sep 26, 2011 5:19 pm
by amigoface
Beauty wrote:To already have the data is a good starting point.

You also need to know, to which real dimension you want to map the texture and terrain data. (e.g. 30 x 30 km²)
This is important for converting to Ogre. In my application I use 1 Ogre unit for 1 meter. (If you use "proprietare" units like miles, you can do it, too.)
For importing the height map you also need to define the height values of black and white.
In the Terrain Scene Manager, black is related to Y=0 in Ogre coordinates. Dependent to your used coordinate system you could need to add a height offset or do more advanced coordinate calculations.
For a flight simulator it could be useful to use a coordinate system, which is common for airplanes. Then you can apply related flight calculations. If you do all calculations in Ogre coordinates you can't use common flight equations. Adopting equations to the Ogre coordinate system could be difficult. In my maritime applications I do the calculations in the North-East-Down coordinate system. Only for visualization I convert them to Ogre coordinates.
Just a little suggestion. :wink:
i have use gdal to match the heightmap and imagery and everything is perfect
but for the moment i want only get the terrain engine working correctly with my data



Beauty wrote: Why do you want to tile the map so much?
You could use 10 x 10 tiles which are related to 300 x 300 height map pixels (100 in total).
I only have experience with the Terrain Scene Manager. This always needs a squared terrain. (Length and width had to be equal.) Maybe this condition is the same for the new Ogre terrain component.
About the details for tiling and loading by Ogitor you should talk in the Ogitor forum topic. The people there know more practical aspects.
the texture i want to drape over the heightmap is large 51200X26624
so i want to tile the geotiff image to get 2048x2048 images

Re: Where to get height maps (real geo information)

Posted: Tue Oct 04, 2011 10:05 pm
by Beauty
For so many tiles I suggest automation.
Search for a way how to make the needed steps scriptable (conversion, splitting, config file creation, copying, ...).
E.g. by command-line commands, source code modification, tools like AutoIt (website, Wikipedia), ...

If you try AutoIt, you can use the recorder to create a script, which you can modify later. Just start the recorder and perform the clicks and inputs in your application(s) to create one tile.

Re: Where to get height maps (real geo information)

Posted: Mon Oct 17, 2011 10:48 am
by amigoface
hi,
sorry for the late reply :mrgreen:

now that i have all my data : png heightmaps + dds texture textures

what the correct scale parameters according to the world size ?
by this i mean input bias and input scale
since i use real world data

Re: Where to get height maps (real geo information)

Posted: Wed Oct 19, 2011 9:45 pm
by Beauty
For my geo data I did know the size. (e.g. 2000 x 2000 m²)
The same X-Z size I set to the terrain.
Also I did know the co-domain of the height. The difference between the highest and lowest point (of the geo height map) I used as world height.
(e.g. co-domain of 1000..1100 m above sea level --> world height = 1000 Ogre units)

In my application I use the Terrain Scene Manager. (It's obsolete in current days, but still good for my own needs.)
The TSM uses scene config files. There I added a reference to the height map and texture file. Also there are parameters for the size of the scene. I suppose you will use the new Ogre Terrain Component and there should be size options, too.

If you know only the Latitude Longitude values of your maps, then you have to convert the coordinates of the 4 corners and calculate the distance in meter (or miles).


Possible useful websites with online calculators for Latitude Longitude:

Latitude/Longitude Distance Calculation
http://jan.ucc.nau.edu/~cvm/latlongdist.html

USGS Great Circle Calculator
http://woodshole.er.usgs.gov/staffpages ... u/ccal.htm

Degrees, Minutes, Seconds and Decimal Degrees Latitude/Longitude Conversions
http://transition.fcc.gov/mb/audio/bick ... cimal.html

LatLong Generator
http://graargh.returnstrue.com/rajdeep/ ... ol_v7.html

Lat/Long-Converter -- Degree to meters/feet/miles
http://www.starpathdemos.com/bowditch/table7.htm

Link list about several LatLong calculators and source codes
http://www.globixworld.com/resources.cfm