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How do you use/download free satellite dem maps for UK.

PostPosted: Tue 20 Dec 2005 - 22:39
by Barry
Several questions as interested in the option we have for downloading FREE satellite data for the UK.

Which sites, what types of files and if posible a small tutorial on how to use them as I have no idea.

Have been looking at the space shuttle site, but completely lost on the ftp download page and don't know even if the files can be used in the dem scenery designer we have. If 90 metres or so probably too large a resolution anyway.

Can anyone give some help/advice to get started making realistic routes.

At present I am using map overlays to trace contours, etc.
Unfortunately the dem editor restricts us to just over 2000 height bars so the resolution soon starts mounting up on larger routes.
Once again considering my 110 mile route bust needs spacing at 88 metres or so x 2000 to get to 110 miles.
Keep going to try it and keep putting it off.

If we had some tutorials available I am sure it woud get more people interested.

Seems very flat the Stentec simulator forums at present.


PostPosted: Mon 26 Dec 2005 - 19:14
by ajnasreddin

I don't know of anything free out there. I looked around a couple of months ago but I couldn't find anything. Not too surprising though considering how much work goes into them - consider how much work you've put into your scenes. I was looking for DEMs for the United States - and nothing is really free in the US anymore. I did find a DEM package offering complete coverage of all waterways and coastlines in the US, for over $400!

Satellite images and mapping are a tricky business because, naturally, the world is round while maps are flat. I can foresee one day when simulators will simulate even the curvture of the Earth - but not any time real soon. If you rely on satellite images, remember that many images are taken at angles and not straight on, so distances will be somewhat distorted. Of course distances get distorted on maps too - especially Greenland (I wonder if they pay for that?).

But for satellite images - Google Earth can be downloaded for free, with fairly good resolution for the developed world.

PostPosted: Mon 26 Dec 2005 - 20:07
by Barry

I think the data on the Nasa site is free and you can download by -ftp-.
Did look at it a while ago but couldn't understand it.

If you go down the page to srtm data (I think it was), second panel. Not sure if it was 90 metre dem(resolution), but even that woud be woth a try.

Will have another look at the site maybe later today.
If we could get discussion going about satellite data etc, on the forum we may get somewhere, and get dozens of routes made by different people,
instead of the few we have now.

We have the dem. software, but nobody seems to be able to get very far with it, myself included, except using it for tracing contours, etc.
Or at least little is posted on the forum about it.

Everything takes too long the way I am making them, and not accurate even for the early 19th Century, especially river systems.
Instead of nice steepish banks they are jagged and sloping with the larger resolutions (spacing). Max scenery size at present is 2048? x metres.

Thanks for posting.


PostPosted: Tue 27 Dec 2005 - 01:51
by Barry
I notice there are convertors for dem file types on other sites.
If any forum members could add to the thread it would be most helpful.
Completely lost myself with the different types of files.
Interested in FREE data, preferably UK, that I could exoeriment with and at least get some sort of Scenery out of it.
Also AJ interested in USA data.
For my part not only need the files but detailed help on how to use them.



P.S.Tried a download of an srtm file which is zipped as hgt.
So how to get that into the dem editor and which fileson the site, if any are UK?
Which convertor and how obtained and will file work?
Just thinking about it as I don't know the answer.

PostPosted: Wed 28 Dec 2005 - 17:36
by Barry
Download an srtm file to see what type it was and now in hgt.
What happens next. Can that be changed to be read by the dem editor.

Sure getting confusing as just download a zip program to open tar.gz.file
First one I download had spyware in it and deleted it.
That was for using GTOPO30
Again can those files be use as it was 8 meg download and covers a huge area.

Can hgt file be used for the srtm sections.
How is it converted as won't open in the dem or VT bulder in Scenery Designer. I seem to be going around in circles on the Internet to find information.


PostPosted: Wed 28 Dec 2005 - 19:18
by Barry
Next...downloaded the free 3DEM at about 4 megs which opens the hgt file and allows all manner of settings and readings

But export as USGS ASCII Dem
GeoTiff Dem
Neither of these file types appear to be openable in the Dem Editor.
or with the VT Terrain Builder that comes with the Scenery Designer.

Must admit at present beginning to get a bit fed up with these simulators.
I know other simulators can create terrain easy enough from dem data, using a variety of programs, and there is plenty of help and advice on those forums.

So can 3Dem be used to export files into the Stentec Dem Editor?
If not back to how to use hgt dem data which can be downloaded.

Maybe the Stentec Dem. Editor is out of date at 3 years old approx?

Can only hope now for a tutorial or detailed explanation on using the hgt file to work in dem editor?


PostPosted: Sat 31 Dec 2005 - 18:35
by ajnasreddin
But export as USGS ASCII Dem

I thought Stentec had a special feild for choosing the DEM types - though I would not be surprised if Stentec uses a European based system and not the American one.

PostPosted: Thu 19 Jan 2006 - 18:10
by Barry
Jeroen from Stentec posted a solution on the SRTM thread in sailing simulator forum.