How to correctly project texture to UV map from 3D scanned object?

Question

I am a beginner in Blender and I am trying to get a 2D image of a scanned object with the texture correctly applied or projected.

As you can see, in the right section I have the 3D object with its texture applied. It is an OBJ file product of a 3D scan. As I was investigating, one way to obtain a projection is through a UV map ("Mark seam" => "Unwrap"). When doing it, I get a 2D object with the desired shape (selected in orange, left section), but the texture is not applied correctly, it is shown in the background without projecting on the faces.

Is there any way to achieve it?

Answer 1

So I hope you learned it by now, just stumbled over it to explain for other newbs: brace yourself as "projecting from 3d scan' is not where the journey should start, to.understand what happens. I try:

You have a 3D scan obj. If you investigate, an obj made with an app (I suppose you used a smartphone) comes already with colorinformation. This is because of a .mat , wich is referenced and automatically opened and applied when you import the .obj. That is the "picture" you see in blender: a automatic uv unwrap, wich are assembled more or less randomly. That is not the important part.

First: Cleanup (Described for Blender)

On a 3d Scan it is always usefull to select a vertex, press Ctrl + L and by doing so select all linked geometry. With shortcut H we hide it and not connected, faulty scan geometry should still be visible. With strg+a select all (visible, false) geometry and delete it. Alt + H to make all visible again. You should be able to display the object in most software/engine now.

When you want to show it as ingame object or optimize it for use on e.g. smartphones, you need to build a low poly model. For doing so please watch the 1000 methods and tutorials (I use TopoGun 3, it pretty much makes a new, organized mesh automatically but you have to know your way around 3d already, to understand it).

The low poly model can not only reference color but also the details and curvature of a "high polycount" model. The process of doing so is called "projection". In order of doing so you need to UV Unwrap the low poly you build (yes, mark seams, unwrap). Then the process applied is generally called baking, when color or other visual information (normals, curvature, ambient occlusion...) Is transferred. For blender you find it in the cycles render engine tab under Bake. Substance Painter and Mormoset 3d also have neat baking overlays.

The best part about blender is the color projection part especially for 3d scans! There is some tutorials out there but anybody reading this should have the keywords to look for now.