Making a 3d topo model

**neck beard** · 07-15-2008, 11:16 PM

Does anyone know of an easy way to do this? I can stencil and carefully cut a thin bit of cardboard for each contour, but that takes huge time and end up not so smooth. I could also attempt to free-model it, but that's just guessing and I suck at sculpture.

As far as I can tell, this just isn't possible without some serious technology.

I wont my model to be about 3'x2'

**Nathan Explosion** · 07-15-2008, 11:30 PM

Assuming you mean a physical 3D model, there's no great way of doing it, unless you have access to some pretty serious technology, like a prototyper or something, and some CAD or SW experience.

Cutting cardboard/foamcore is admittedly a huge pain, but not terrible, though I don't know the size of the model you're making. If you need some suggestions, feel free to PM me.

**XavierD** · 07-15-2008, 11:45 PM

While less accurate a fast method would be to use pink insulation foam and use a hot wire to cut it into the shapes you need using say 1/4 or 1/2 inch thick boards.

**neck beard** · 07-16-2008, 03:33 AM

The pink foam sounds challenging for me as its kind of nor reversible - I would make a lot of mistakes and get the scale wrong as well, needing to fillout areas I had previously cut. Perhaps some kind of resin would do well where I can carve it up and then add volume again in case I make a mistake.

Nathan - benefit of the doubt here. Yes, a physical model. I want to convert a 1:25,000 map into a 2'x3' model.

**Nobody Famous** · 07-16-2008, 04:40 AM

If you can get the cardboard figured out, then cardboard for the 'frame', then cheesecloth dipped in plaster draped over the 'frame'. Some food coloring in the plaster will make it look brown or green.

**schuss** · 07-16-2008, 01:06 PM

Print out topo, lay over foamcore (will likely need two sheets to ensure proper overlap for mounting). Cut on topo lines (likely every other in layers like an onion), stack and glue.

Now smooth with putty of choice.

**EarlyWood** · 07-16-2008, 05:56 PM

Originally Posted by Hohes

Does anyone know of an easy way to do this? I can stencil and carefully cut a thin bit of cardboard for each contour, but that takes huge time and end up not so smooth. I could also attempt to free-model it, but that's just guessing and I suck at sculpture.

As far as I can tell, this just isn't possible without some serious technology.

I wont my model to be about 3'x2'

you have way too much time on your hands

;-)

**neck beard** · 07-16-2008, 09:54 PM

Originally Posted by schuss

Print out topo, lay over foamcore (will likely need two sheets to ensure proper overlap for mounting). Cut on topo lines (likely every other in layers like an onion), stack and glue.

Now smooth with putty of choice.

I don't quite get this one.

"Stack and glue" = you mean cut out a layer for every contour line, the 'standard' approach. Or are you explaining something else?

Earlywood: I do you know. Right now I was supposed to be farming and building/renovating a house. But late in the game we decided it is way better to rent than buy and now I left my run too late.

**TomK** · 07-17-2008, 12:20 PM

Here's some inspiration:
http://www.howardmodels.com/Topography/

Basily, they use CNC cutters to make each elevation and then stack and glue.

Other tools are available to do this, (Epilog Laser cutters for example), but they are pretty pricy for a one-off or hobby use. (for 2x3 feet, think 10-20 grand. Used)

**schuss** · 07-17-2008, 01:20 PM

Originally Posted by Hohes

I don't quite get this one.

"Stack and glue" = you mean cut out a layer for every contour line, the 'standard' approach. Or are you explaining something else?

Earlywood: I do you know. Right now I was supposed to be farming and building/renovating a house. But late in the game we decided it is way better to rent than buy and now I left my run too late.

Yes. When I did this back in grade school from a topo, I cut out on each topo line. It's not that bad, really, just takes a little while. Also setup two sheets so you can have 2 topo lines worth on each cut for easy stacking. Also makes it easy to line up the next one.

**Nathan Explosion** · 07-17-2008, 02:32 PM

Originally Posted by Hohes

The pink foam sounds challenging for me as its kind of nor reversible - I would make a lot of mistakes and get the scale wrong as well, needing to fillout areas I had previously cut. Perhaps some kind of resin would do well where I can carve it up and then add volume again in case I make a mistake.

Nathan - benefit of the doubt here. Yes, a physical model. I want to convert a 1:25,000 map into a 2'x3' model.

A good place to start would be to determine how many levels/layers you're going to need, or at least get a good estimate. I'm assuming it's some kind of mountain, so count the levels from the lowest elevation to the peak, and then guesstimate how many of those levels you can get out of the same sheet.

I think foamcore is about the easiest to work with for something like this, all you need is a good x-acto or box knife, and it looks very clean, at least to me, and you don't need anything but simple Elmers or rubber cement.

**TomK** · 07-17-2008, 03:58 PM

Originally Posted by Nathan Explosion

...
I think foamcore is about the easiest to work with for something like this, all you need is a good x-acto or box knife, and it looks very clean, at least to me, and you don't need anything but simple Elmers or rubber cement.

Yeah, 1/8th inch foamcore would be easy to work with. (1/4 inch would end up way too thick methinks.)
Suggest using 3M's Super 77 spray adhesive, not a water-based glue like Elmers.

**neck beard** · 07-17-2008, 08:49 PM

Schuss - Thanks man. The only bit I'm not understanding is this "Also setup two sheets so you can have 2 topo lines worth on each cut for easy stacking."

Here is a topo sample from the model terrain.

Assume that is printed on an A4 sheet in landscape. The full model would be approx 2 sheets wide and 6 long.

In terms of contour lines, there are about 120 of them. So speaking in metric, I'd be going for sheet 2mm thick giving a total relief of 240mills (24cm)

**Nathan Explosion** · 07-17-2008, 09:02 PM

Yeah, spray would be easier. I probably should've mentioned that I paint the Elmers on so thin it's the approximate equivalent, I'm just cheap.

That map is going to be a pain in the ass, but considering the size you're working on, you definitely need to get it printed so that you can look at it versus your model 1:1. The really lazy way of progressing after that, is to cut the individual layers out, and use them on whatever material you've chosen for use. At the size you're working with, they should be pretty usable, and then you can get a real idea of how much you can get out of each sheet of material.

**snoboy** · 07-18-2008, 08:04 PM

OK... you might be able to use a raster to vector conversion program and get that image turned into lines, and then get the shapes cut at a commercial service place. I've never tried this, but if it works it could be a lot less work.

Pretty sure schuss means to cut every other line out of one sheet, and then cut the other lines form the second sheet. That way the 500m layer will have somewhere to sit on the 450m layer (for example).

This should be sweet when it's done. What is it for???

**khakis** · 07-19-2008, 03:53 PM

Originally Posted by snoboy

OK... you might be able to use a raster to vector conversion program and get that image turned into lines, and then get the shapes cut at a commercial service place. I've never tried this, but if it works it could be a lot less work.

This is actually a really good idea. Even better would be if DEM or LIDAR (thinking Japan with all it's water-related risk issues might have invested in this) data were available, and you could have a GIS nerd process it and make you a shapefile of contour lines at whatever interval you want. Convert shapefile to dxf and any machine with CAD should be able to cut it out. Availability of data and a cad foamcore cutter could be limiting, however.

**neck beard** · 07-21-2008, 08:12 AM

Originally Posted by snoboy

This should be sweet when it's done. What is it for???

Just for the love of the mountains. Having a model of the mountains you ski in is really useful. The French made a really good one for the Chamonix area (which is hanging on my wall). Its my #1 possession. If I made one by hand for my new home then I think it would become my new #1. That way the few people I know who actually give a shit about talking + hitting routes can come and stand around the model and drink beer and... talk routes.

I have loads of DEM data (which for some reason confuses me, I don't really know what it is). But the cutting/shaping hardware sounds way beyond my reach.

I have casually started to look for someone locally that can make it. Perhaps a university. Though I'd love to craft it myself.

**snoboy** · 07-21-2008, 11:47 AM

The hardware is probably out of reach for you to own, but there should be someone who can charge you to cut. Such as: http://www.pololu.com/catalog/product/749

We want pictures

**khakis** · 07-21-2008, 12:33 PM

Originally Posted by Hohes

I have loads of DEM data (which for some reason confuses me, I don't really know what it is). But the cutting/shaping hardware sounds way beyond my reach.

It's basically just a file that describes a grid, where to place it on the globe and has elevation values for each square on the grid. You need a software that knows how to process it (think there may be free viewers out there), but to do what I described (generate custom contours and export to CAD) will take ArcMap and 3d Analyst. I happen to know a guy who has access to such things