Topo Maps (UK)

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Topo Maps (UK)

Postby davekenyon » Wed Oct 18, 2017 7:54 pm

Hi,

Sorry to reopen what might, to some, be an old topic but I've searched the forum and am now thoroughly confused! I'm encouraged by this: http://www.tomfurniture.co.uk/contour-boxes

I'm looking to generate 3D models of mountainous areas in the UK. I can find various sources of data, ranging from OS Terrain 50 and down to 1m LIDAR data.

I've had a go at Terrain2stl but it doesn't seem to give the detail I'm after. Had a quick go at BigTopo but not sure that has the detail either. At absolute maximum resolution, I'd really like to be able to model a 3x3km square onto 60x60cm.

The OS Terrain 50 data doesn't merge well in MicroDEM (trenches and black spots/spikes). I'm just about to start importing and merging 2m LIDAR in MicroDEM. It's difficulty pick the exact area I need, and importing a large regions seems to be a long job and possible overkill for the resolution I need!

Could anyone suggest a way forward?!

Thanks.
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Re: Topo Maps (UK)

Postby LittleGreyMan » Wed Oct 18, 2017 9:13 pm

Hi Dave,

Modeling a 3km square into a 60cm square gives a resolution of 5m/mm, as you probably already know.

Obviously, if the resolution of the file is 5m/mm, you'll get one point per millimeter which will look very rough. The 1m LIDAR data is obviously the only choice. 5 points per millimeter sounds OK.

I never used such files, so I don't know if BigTopo can process them. Paul will probably chime in if he's not on his boat or running some dangerous experimentation in his lab :D

If it does, it's probably the most friendly tool as it will "sew" contiguous files (according to Murphy's law, the area you choose is ALWAYS at the intersection of at least 2 files) and allow the use of coordinates to select the area.

You may encounter some problems with mountainous areas as files may include numerous artifacts. BTW, are you sure you've got mountains in the UK? :mrgreen:

Hope this helps
Best regards

LGM

W7 - Aspire 8.517
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Re: Topo Maps (UK)

Postby davekenyon » Wed Oct 18, 2017 9:28 pm

Hi LGM,

Thanks for the input.

They certainly feel like mountains when I'm walking!

Cheers.
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Re: Topo Maps (UK)

Postby PaulRowntree » Thu Oct 19, 2017 4:56 am

Hi Dave
Unfortunately it has been almost a boat-free summer, and my lab is being rebuilt :(
The sat data for UK is on a ~90mx90m grid, so a a 30kmx30km area would be ~300x300 real data points. for a 600x600mm cut, that is a point every 2mm. BigTopo can try to interpolate a finer grid if you want, and the stl file can be smoothed if faceting is visible.

As a free program, BigTopo is written to use freely available data files. It cannot read other formats. More file flexibility would be nice, but that might be moving towards a specialized product, perhaps a commercial one. Hmmm, retirement looms ... :)

If anyone knows of other, free data sources that cover the globe, I would see about adapting BigTopo.

Dave, can you tell me the area that you are interested in ? I will see what I can do ...

Cheers!
Paul Rowntree
WarpDriver, StandingWave, Topo and gadgets available at PaulRowntree.weebly.com
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Re: Topo Maps (UK)

Postby davekenyon » Thu Oct 19, 2017 9:16 am

Hi Paul,

I've sent you a PM with the area I'm interested in.

Many thanks.
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Re: Topo Maps (UK)

Postby PaulRowntree » Thu Oct 19, 2017 3:34 pm

Snowdon 1.png
Here is that area, in a 10 km x 10 km area, with 50mx50m pixel grid. Does it look about right ?

This is a screenshot from BigTopo ... smoothing could be done on the STL file in Meshlab ..

Smaller areas work, but have the limited resolution and miss the context of the surrounding landscape.

https://www.google.ca/maps/place/Snowdo ... 66!5m1!1e4
Paul Rowntree
WarpDriver, StandingWave, Topo and gadgets available at PaulRowntree.weebly.com
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Re: Topo Maps (UK)

Postby davekenyon » Thu Oct 19, 2017 4:01 pm

Hi Paul,

The area is spot on thanks, and I understand your point about the wider context. I think smoothing would lose too much detail, so I think I'll have to go with widening the area.

Cheers!
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Re: Topo Maps (UK)

Postby AJF » Thu Oct 19, 2017 9:24 pm

Where I live (Yukon, Canada) the level of fine detail for most DEM files is not that great. So I've been looking around for other ways to create detailed topo maps and came across a series of videos using Sketchup that you might find interesting. I haven't tried all the ideas presented in these videos, but so far it has been a interesting learning experience. https://www.youtube.com/watch?v=PE8gQfFaqjg
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Re: Topo Maps (UK)

Postby PaulRowntree » Fri Oct 20, 2017 5:11 am

Here is the load file that creates that STL. Copy the text into anything.BTD, then load it by Parameters | Load ...

Increasing the Z Extent to 2.0 can make this look more dramatic :)

[Notes]
Author=Paul Rowntree
Date=2017-10-19

[ROI]
Long1=-4.1516
Long2=-4.002
Lat1=53.0231
Lat2=53.1131
Z1=0
Z2=1500
Long0=-4.0768
Lat0=53.0681
dLong=10
dLat=10

[Sizes]
X=5
Z=0.5
ZBase=0
NaturalZ=0
XY_Pixel=50

[Flags]
Block_SRTM1=0
BlockSRTM3=0
BlockSRTM30=0
MissedData=0
ZeroNormals=0
RenderFlat=0
AutoRebuild=0

[Files]
STL=C:\temp\NewFile.stl
Paul Rowntree
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