Making a 3D topo map of my town - looking for techniques

[DaveC426913]

TL;DR Summary

Trying to figure out a practical way of making altitude layers for this relief map

I hope to make a 3D relief model of my town and environs.

First, rough idea, it will be 1m by 0.5m at 1:10,000. That will give me a map of the area 10km by 5km. Sort of this-ish:

As you can see, it's quite flat here, both abov e and below the escarpment. If I were to keep the vertical scale, that would make the plateau ("the mountain" is what it's called here) only 1.5cm high, and the rest would be as flat as a pool table. So I might boost the vertical scale by 5 or so. Even that gives me a total height of only 7.5cm.

(I haven't decided yet whether I want to smooth out the contours or leave them stepped.)

What I am trying to do is figure out how I can build the relief economically, cost- and effort-wise.

My first attempt was to cut out the altitude contours from sheets. At 150m, I might settle on 10m contours, which would make for 15 or so layers, each .5cm high.I printed out the contour maps of the area and glued then into foam core, and cut along the contour lines. That did not go nearly as well in reality as it did in my head. Even with an Xacto knife, the edges were mangled and the paper cut very poorly. I tried a hobby saw (just a toothed wire held taut between prongs) and that went poorly. I tried a hot wire, which also went poorly.

So I tried balsa sheets. This went pretty poorly too. I have to use the Xacto knife to saw, so I get a pretty rough, faceted edge.And there's yet another problem: Half my map is going to be 7.5cm thick and solid. That's a lot of material - and at quite a cost. I considered hollowing out everything under the mountain but - while that may save me some weight - it doesn't really save me materials. I just end up discarding a lot of it.

It's too big to 3D print, so I'm trying to do some lateral thinking and seeing if there's any methods I haven't thought of.

 

[johntpl]

TL;DR Summary: Trying to figure out a practical way of making altitude layers for this relief map

I hope to make a 3D relief model of my town and environs.

First, rough idea, it will be 1m by 0.5m at 1:10,000. That will give me a map of the area 10km by 5km. Sort of this-ish:

View attachment 328431

As you can see, it's quite flat here, both abov e and below the escarpment. If I were to keep the vertical scale, that would make the plateau ("the mountain" is what it's called here) only 1.5cm high, and the rest would be as flat as a pool table. So I might boost the vertical scale by 5 or so. Even that gives me a total height of only 7.5cm.

(I haven't decided yet whether I want to smooth out the contours or leave them stepped.)

What I am trying to do is figure out how I can build the relief economically, cost- and effort-wise.

My first attempt was to cut out the altitude contours from sheets. At 150m, I might settle on 10m contours, which would make for 15 or so layers, each .5cm high.I printed out the contour maps of the area and glued then into foam core, and cut along the contour lines. That did not go nearly as well in reality as it did in my head. Even with an Xacto knife, the edges were mangled and the paper cut very poorly. I tried a hobby saw (just a toothed wire held taut between prongs) and that went poorly. I tried a hot wire, which also went poorly.

So I tried balsa sheets. This went pretty poorly too. I have to use the Xacto knife to saw, so I get a pretty rough, faceted edge.And there's yet another problem: Half my map is going to be 7.5cm thick and solid. That's a lot of material - and at quite a cost. I considered hollowing out everything under the mountain but - while that may save me some weight - it doesn't really save me materials. I just end up discarding a lot of it.

It's too big to 3D print, so I'm trying to do some lateral thinking and seeing if there's any methods I haven't thought of.

Hi, DaveC,

A million years ago (give or take) I made architectural models and had to do this very often. We used rigid urethane foam. It’s available in different densities. We used lighter foam for smoothed contours, heavier if left stepped. Doing this by hand is tedious and very messy-a lot nasty dust gets made. We had a DIY 1/1 pantograph cutter with a vacuum attachment-it was still nasty.

Depending on your budget, you could have the topo cut by a topo shop. You might be able to find one online or go to an architectural model shop. When I was in business 30 years ago a topo of the size and detail you’re considering would cost around $250.

Good luck,

John

 

[DaveC426913]

Depending on your budget, you could have the topo cut by a topo shop. You might be able to find one online or go to an architectural model shop. When I was in business 30 years ago a topo of the size and detail you’re considering would cost around $250.

I guess, yeah. That's a service now. You just give them your coords and a scale (and some cash) and they send it to you engraved in some nice wood.

 

[BillTre]

My wife has a paper cutter (consumer grade) but I doubt but things that it will cut things that thick. But a commercial fab shop might be able to it for you.
Alternatively, a commercial laser cutter might be able to do it.

 

[Baluncore]

TL;DR Summary: Trying to figure out a practical way of making altitude layers for this relief map

It's too big to 3D print, so I'm trying to do some lateral thinking and seeing if there's any methods I haven't thought of.

1. Cut layers with a cheap small x-y NC router, from a sacrificial material, in smaller pieces that will fit together. During fabrication, different thicknesses and materials are OK.
2. Maybe profile the cut edges by controlling thickness with the z-axis.
3. Assemble, then if there are any gross asperities, grind or sand the landscape. Include a flat-earth step at the sides to stand it up and give it strength later.
4. Place the approximate model inside a plastic or rubber bag, shrink on with a vacuum. The thickness of the material will decide the surface averaging and the gloss finish.
5. Make a papier-mâché or fibreglass mould / copy from the model.
6. To prevent mirror reflections, paint the surface with matt paint, or paste glue and sprinkle fine sand.

 

[Tom.G]

I made a small one, about 16 inches square and 5 inches high, a couple years ago.
I used foam board and glued the maps on with rubber cement. Cutting was done with an X-Acto knife and MANY No. 11 blades (the cuts get ragged with a dull blade). Tracing the coutour line for each layer with a contrasting color (I used Blue) was a big help. Following/cutting a convoluted line without that extra cue is... Umm... 'difficult'.

A sealant was needed after assembly because an ink-jet printer was used. Spray-cans of sealant did NOT work well - they dissolved the ink! An artist neighbor had some brush-on sealant that did the job if applied in a very thin, almost dry, layer.

One trick was realizing that the smaller (higher elevation) pieces could be cut from the center of a larger, lower elevation, layer. That reduced the printing and gluing operations too. Of course I realized this after the first couple layers were assembled; but it worked out OK. On completion, a couple holes in the base layer were cut to insert thumb and forefinger to hold the map up for display. Those finger holes needed sealant too, not only to hold the material together, but the edges are rough enough to make your fingers sore.

A small (5.5 x 8.5 in.) legend sheet with a brief explanation was also printed, mounted on scrap foam board, and displayed on a cheap wire stand from the local stationary store.

It was on display in the Community Center for a month or so and then donated to a local primary school.

Have Fun!
Tom