Display Mode to hightlight geometric changes?

So I do quite a bit of work with annotating scanned real-life objects, and the annotation part of the workflow is done in Rhino. Occasionally I’ve found myself wishing for a Display Mode, that would highlight geometric changes on the mesh surface - particularly to locate wear or tool marks on the surfaces. I’m thinking of something like a height or slope map, but for a 3d object. Possibly something that would colour code angular differences between polygons?

Does anything like that exist, either as an analysis tool or plugin?

Edit. so far, I use either the shaded view or rendered view with increased glossiness on the texture file, to make the surface geometry pop out. But that method is dependent on the kind of light source that’s used and the angle of the camera relative to the object.

Hi Benjamin -

In a way, that would require Rhino to know the original state of the object, which it obviously doesn’t.
I’m thinking that, perhaps, a normal map might be the way to go. At least you would see local variations of the normals and can then - yourself - decide if those variations are the result of the design or of the wear. Rhino has the TestShowNormalMap test command. Does that do any good? Can you post a simple example of an object on which you would use this?
-wim

1 Like

Hi Wim,

Thank you for your reply!

To your first point, regarding the identification/recognition of wear and tool marks, that is a matter of archaeological interpretation on my part - and not something I would trust a piece of software with. I’ve posted a screenshot below to give you an idea of what a typical object could look like:


What you see is a scanned 3d model of waterlogged timber from a 17th-century shipwreck (specifically, a futtock). Off to the right are a number of different colour-coded layers we use to annotate different features of the worked timber. Usually, when the timbers are well-preserved, it is easy to distinguish edges and geometric changes on the mesh, in order to interpret what those features are. This usually requires moving the camera around a lot, for the shading to reveal the changes in the surface/mesh geometry - in tandem with the texture. But this is not always the case, especially when the surfaces of the original object are weathered or have been scoured by sediments. As I mentioned, in the OP, using the shadows or gloss as guiding lights towards finding patterns in said geometry is alright, but the process would be accompanied well by a ViewMode that could colour code according to the degree of surface changes - possibly using angular differences between individual (or maybe groups of) polygon?

Below is a screenshot of the same model, but with the TestShowNormalMap command turned on. Essentially, this mode accomplishes the same as a high-gloss rendered or shaded ViewMode does - albeit with prettier colours :slight_smile:


That is to say, that test command doesn’t exactly hit the head of the nail, I’m trying to describe - if that makes sense?