====== Topophane ======

===== About =====

This project exists to create a topographic lithophane that conforms to my aesthetic preferences. Typically when you print a topographic map out of a semi-transparent plastic you automatically get a sort of lithophane. The effect is cool, but there are a couple things I don't like about it. First, the maximum elevation in a print is determined by the transparency of the material and the minimum elevation is determined by about two times the minimum layer height of a given printer. This means that if your material is fully opaque at 1cm thickness and your minimum layer height is 0.1mm your maximum height difference is 9.8mm. Second, you have no control over whether the peaks are light or dark, the peaks are necessarily dark when backlit in a standard topographic print.

The root cause of these problems is that the standard lithophane has a flat back plane. The solution is dynamically generating not only the front surface but the back surface as well. This project is a python script that reads in DEM (Digital Elevation Model) data as TIFFs and produces a manifold STL that can be sliced using standard slicing software.

<figure>
{{:kb:proj:ftg:topophane:dem_light_valley.png?direct&200|Dark Peaks}}
<caption>Dark Peaks</caption>
</figure>
<figure>
{{:kb:proj:ftg:topophane:dem_dark_valley.png?direct&200|Light Peaks}}
<caption>Light Peaks</caption>
</figure>


===== Features =====

  * Set minimum and maximum height arbitrarily (terrain exaggeration)
  * Set minimum and maximum material thickness (material calibration)
  * Choose whether peaks or valleys should be dark
  * Process square and arbitrarily shaped DEM data
  * Generate a lip  of arbitrary height and width around the edge of the model

===== Progress =====

I currently have the script successfully importing and transforming DEM data, but I am struggling through the STL generation. The main problem is adding the lip in a way that is consistent and manifold for arbitrarily shaped models.  It is clear that my core understanding of how the data inside of an STL is structured is lacking.

{{tag>projects in_house current}}