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"UK DEM Data Update"

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branchline (7 posts)
Aug-15-01, 06:17 AM (EST) "UK DEM Data Update" Many thanks to all those people who offered advice on how to import DEM Data for UK routes. The unfortunate conclusion for me is that the data available free for the UK is of little value in constructing routes. I have been attempting to import DEM data for my Reading to Henley-on-Thames branch project for over two weeks and just getting a flat green carpet. today I thought I would experiment and try a mountainous area of the UK ie; the Lake District and here is the result.

That means that I have been successfully importing the DEM data for my area all the time its just that anthing below 100m dosn't show up.
Thats a shame as I'm sure the navies who died cutting the sonning gap wouldn't call the 70m hill they had to cut through insignificant.
Oh well back to manual height adjustments untill OS start delivering better quality data. Alert Edit | Reply | Reply With Quote | Top
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Subject Author Message Date ID RE: UK DEM Data Update oudrun Aug-15-01 1 RE: UK DEM Data Update Geordie21 Aug-15-01 2 RE: UK DEM Data Update eveningstar Aug-15-01 3 RE: UK DEM Data Update richrailart Aug-15-01 4 RE: UK DEM Data Update branchline Aug-16-01 5 RE: UK DEM Data Update richrailart Aug-16-01 6 RE: UK DEM Data Update eveningstar Aug-16-01 9 RE: UK DEM Data Update richrailart Aug-16-01 14 RE: UK DEM Data Update Geordie21 Aug-16-01 7 RE: UK DEM Data Update richrailart Aug-16-01 8 RE: UK DEM Data Update Geordie21 Aug-16-01 10 RE: UK DEM Data Update ianm42 Aug-16-01 11 RE: UK DEM Data Update Geordie21 Aug-16-01 12 RE: UK DEM Data Update ianm42 Aug-16-01 13 RE: UK DEM Data Update Geordie21 Aug-17-01 15 RE: UK DEM Data Update richrailart Aug-17-01 16 RE: UK DEM Data Update eveningstar Aug-19-01 17 RE: UK DEM Data Update richrailart Aug-19-01 18 RE: UK DEM Data Update eveningstar Aug-19-01 19

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oudrun (19 posts)
Aug-15-01, 09:05 AM (EST) 1. "RE: UK DEM Data Update" Thats strange. I've been doing some terrain in Norway, and I get slopes and hills all the way from high altitude donw to about sea-level.Done a lot of terrain in the lower part of Norway, with ok result even if DTED-0 data isn't that great.RuO Remove | Alert Edit | Reply | Reply With Quote | Top
Geordie21 (27 posts)
Aug-15-01, 10:47 AM (EST) 2. "RE: UK DEM Data Update" sorry to hear about the probs with the data, its the same data ive been using. Same problem, not that ive looked more closely! How do you manually edit the terrain? Also, and perhaps more importantly, how do you know what the terrain should look like?
-Cheers Remove | Alert Edit | Reply | Reply With Quote | Top
eveningstar (12 posts)
Aug-15-01, 04:36 PM (EST) 3. "RE: UK DEM Data Update" Branchline, you're not alone in your route building problems, I think the problem is that the DTED-0 Data for the UK is averaged out (i.e. low-resolution) so all the little hills and valleys that make the route interesting look like a gentle slightly uneven plain! The route i'm working on has a 17 arch viaduct but looking at the resultant terrain it looks like it's going over a very wide ditch! My route goes from about 5m elevation to no more than 100m elevation (but pretty hard work for a steam engine). I believe that there is much more detailed DEM data for the UK available from the Ordnance Survey (OS), (there must be - I doubt that the Settle & Carlisle terrain in MSTS was created using the route editor!!) but unlike the USA, where they obviously insist that work funded by tax-payers should be freely available to tax-payers, in the UK the OS expect Mr and Mrs Taxpayer to pay up... again. I dread to think how much they will charge for detailed DEM data (as a comparison, at work we have to pay about £30.00 for an A4 sized digitsied 1:1250 plan). Rant Over.I don't even want to contemplate manually editing the terrain, it would just take forever and will never look like the real thing, which is kinda like the point man. The other option I'm exploring is vectorising the data from an OS map. How? - well basically the idea is that you can use software to trace contours off a scanned OS map and tell the software what height each contour lies at. This is a rather time-consuming process (especially when you start tracing a convoluted 10m contour and find out that when you get back to where you started you're on the 20m contour - d'oh!) This information can then be saved as data which, in theory can be imported into John Stanford's DEM-Ex utilty and used to create accurate terrain. The only big problem (well there hand to be at least one!) is that the freeware software i've tried (R2V and Wintopo) are both crippled versions of the full software and suprise suprise you can't save the data in the format needed to import into Dem-Ex. Of course I could pay for the full package, but Wintopo is £140.00 and after all I'm doing this for a bit of fun, not for commercial gain.Geordie, if you get hold of the Ordnance Survey Landranger (1:50000) series for the bit of route you're interested in, you will see that the map has 10m interval contours all over it (unless you live in East Anglia ;)) - well there's your terrain! For more detailed terrain you can get the 1:25000 Pathfinder series which has contours at 5m intervals. For both maps you can look at the railway routes and it will show the embankments and cuttings. I would be interested to know if anybody has any success in creating detailed and accurate UK terrain (ok apart from people in East Anglia).Paul Remove | Alert Edit | Reply | Reply With Quote | Top
richrailart (41 posts)
Aug-15-01, 05:17 PM (EST) 4. "RE: UK DEM Data Update" There is an easier way of importing contours from OS maps - take a look at Microdem.
In the IN/OUT menu, you will find under 'create', digitize scanned contours. Follow the instructions. The only problem (and it is a problem) with this is the primitive interpolation method, the help menu says that 'proper' interpolation is only available with the DOS version of the programme, but I can't find any reference to a DOS version on the home page.
The results are not bad, but you can still have problems - the help explains why.
If the DOS version of Micrdem can be found, then all our problems should be answered.
I only discovered this on Sunday, and I am still experimenting, but I am amazed that none of the experts have mentioned it. Remove | Alert Edit | Reply | Reply With Quote | Top
branchline (7 posts)
Aug-16-01, 08:17 AM (EST) 5. "RE: UK DEM Data Update" I just had a look at this in microdem and it appears to be quite difficult. Will it, for instance, create a file that can be imported into MSTS using DEMEX? Will it read a scanned ordinary map i.e, with contour lines and roads and buildings ect? or do you need special contour maps to acheive this?I know you only discovered it a few days ago so you havn't yet been able to explore in detail. I for one would be very interested in your research.However, in the mean time I have spent so much time looking for ways of getting height data in I haven't made any progress in getting my route started. So for now I am going to use the tools that have helped so far, then manually modify those areas that don't look right. I will be working on small areas at a time i.e, no more than 16 tiles^2, possibly even smaller. I will use marker files as so far they give the best development time against frustration coefficient.Ray Remove | Alert Edit | Reply | Reply With Quote | Top
richrailart (41 posts)
Aug-16-01, 01:43 PM (EST) 6. "RE: UK DEM Data Update" Just scan any 1:50000 OS map at 300 dpi (for clarity - you can get away with less), save as a BMP and off you go. DONT set any elevations to 0, for water put a - value. Demex has no problems (latest version). Try different grid values for the best result.
The only problem I am having is registration of the second map scan. Where the scans overlap I have an error of about 1km that I can't explain.
Compared to some of the procedures in Microdem, this one is easy. Remove | Alert Edit | Reply | Reply With Quote | Top
eveningstar (12 posts)
Aug-16-01, 04:38 PM (EST) 9. "RE: UK DEM Data Update" Ok, thanks for the info... I've had a dabble this evening with Microdem - and I've ended up with an xyz file which contains lines of data as follows;325593 5642685 50
325586 5642707 50
325596 5642731 50
325615 5642756 50
325629 5642780 50
325644 5642805 50
325654 5642830 50
etc.I know the 50 is the elevation (cos i set that)and so I assume the first bits are the eastings and northing in UTM? Does this look right? There is no header info in this file just a list like this. When I first register the scanned image, I do this with three points in lat/long but I can't get a lat/long reading when moving the cursor around the screen - only the figures resembling above e.g. x=324068.58 y=5644545.4. There is no way of undoing the contouring process so it looks like you haveto be right on the button when tracing the contours. Finally, once the xyz file has been created, what needs to happen to it before importing into DEM-Ex - if I try to import the above into DEm-Ex it reports "invalid zyx data or order"Paul Remove | Alert Edit | Reply | Reply With Quote | Top
richrailart (41 posts)
Aug-16-01, 06:24 PM (EST) 14. "RE: UK DEM Data Update" No - don't use lat/long. Use the UTM converter to get the coords for the refs.
I pencilled in the ref points lat/long before I scanned at first, and then converted from the screen, but a better way is to use GPS Utils and list your 3 chosen points.
What you have still to do is import your xyz file to make a grid. This is why Demex does not recognise the file. When the screen comes up with all the fill in boxes, just enter. The only one to fill in is the interval for the grid (I am writing this from memory, so there may be other options, but just enter).
This will give you a gridded xyz file, which Demex recognises.
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Geordie21 (27 posts)
Aug-16-01, 02:13 PM (EST) 7. "RE: UK DEM Data Update" Paul,thanks for your email. Ive already bought a 1:25000 explorer map for part of the track (tell you what mind, if im going to try to do the uk east coast main line it going to cost a bomb in maps!) it looks good scanned, but used up STACKS of RAM when scanning, did it at high res. Ive got the map, but it sounds like we need this microdem dos effort. ive sent microdem and email, awaiting a reply.....Geordie Remove | Alert Edit | Reply | Reply With Quote | Top
richrailart (41 posts)
Aug-16-01, 03:36 PM (EST) 8. "RE: UK DEM Data Update" Have you tried your library for OS maps?
I have had a reply from Peter Guth (Microdem);

"I don't have a copy of the DOS program, and have no way at present to recreate it. At one time it on the the US BLM server
http://www.blm.gov/gis/

That section should be removed from the help file, since I'm not likely to figure out exactly how to do it (and make changes to the code) and then document. From my perspective that side of the business is something that's not a core function of the program."When you get there, you will find an Alladins cave of mapping programmes, so if you find it before me, then please let us know. Remove | Alert Edit | Reply | Reply With Quote | Top
Geordie21 (27 posts)
Aug-16-01, 04:39 PM (EST) 10. "RE: UK DEM Data Update" hi lads,
i just got a reply from the guy at microdem, suggesting to try these two websites. i thought id post so you can have a look - i dunno what to look for! i think one is the same as what you already have.
http://www.blm.gov/gis/the one below is for terrabase, which is apparently the same as microdem.
http://www.wood.army.mil/TVC/ Remove | Alert Edit | Reply | Reply With Quote | Top
ianm42 (240 posts)
Aug-16-01, 04:46 PM (EST) 11. "RE: UK DEM Data Update" Do you know what version we are looking for? The oldest version at that site is 7.58ftp://ftp.blm.gov/pub/gis/microdem/Ian M. Remove | Alert Edit | Reply | Reply With Quote | Top
Geordie21 (27 posts)
Aug-16-01, 04:49 PM (EST) 12. "RE: UK DEM Data Update" hang on ill try to find out Remove | Alert Edit | Reply | Reply With Quote | Top
ianm42 (240 posts)
Aug-16-01, 05:00 PM (EST) 13. "RE: UK DEM Data Update" Oops, sorry, the oldest there is 7.62 - manuals are for 7.43 which appears to be a DOS based version. Remove | Alert Edit | Reply | Reply With Quote | Top
Geordie21 (27 posts)
Aug-17-01, 09:19 AM (EST) 15. "RE: UK DEM Data Update" hi,
just found out that if the version is pre - 8.0 then it is dos. i dunno if this helps... Remove | Alert Edit | Reply | Reply With Quote | Top
richrailart (41 posts)
Aug-17-01, 03:51 PM (EST) 16. "RE: UK DEM Data Update" All the files appear to be dos versions, but running them is another thing. Has anybody the experience to set up these programmes ? When you click on Microdem, the dos window opens with the message 'your pop up program is ready to run'. Then what?
Anyway, I am getting good results from the windows interpolation by setting digitize to continuous with 20 pixels set on a 300dpi scan and using a 30m grid. The more contours and spot heights the better, so put some 5m ones in between the 10m ones from the 1:50000 scale maps. Remove | Alert Edit | Reply | Reply With Quote | Top
eveningstar (12 posts)
Aug-19-01, 05:08 AM (EST) 17. "RE: UK DEM Data Update" Rich,you said above:"What you have still to do is import your xyz file to make a grid. This is why Demex does not recognise the file. When the screen comes up with all the fill in boxes, just enter. The only one to fill in is the interval for the grid...This will give you a gridded xyz file, which Demex recognises."The import in Microdem is, I assume, from the menus:
in/out / import / asciixyz fileYou are asked for an x and y data spacing interval - do you know what the grid should be (30m as above)?. Finally once you've done this it saves the data as a dem file. Do you then need to export this to an asciixyz full dem/utm file?Thanks for the help.Paul
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richrailart (41 posts)
Aug-19-01, 08:05 AM (EST) 18. "RE: UK DEM Data Update" Sorry I was a bit brief with the instructions.
Import from ascii xyz to create DEM, then export as utm file, as you have worked out. I use a 30m grid, but you can try any size.
When digitizing, I am now using 10 pixels on a 300dpi scan.
This is labour intensive, because you must always remember that the interpolation method uses the nearest point, so the more different value levels the better, but you will be surprised how easy it is using the continuous method. Remove | Alert Edit | Reply | Reply With Quote | Top
eveningstar (12 posts)
Aug-19-01, 02:52 PM (EST) 19. "RE: UK DEM Data Update" Thanks,I'll let you know how I get on with my sample area.Paul Remove | Alert Edit | Reply | Reply With Quote | Top

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