Model surface geometry to texture

Entering into a sector I did never approached, I got a 6M poly model with no textures, want to prepare it both for HF and web usage.

Reduced to 25k poly I want to convert the surface geometry of the high poly into a texture .

Since HF is compared with  game engines I did look at various tools used here for the same goal, appear the task is called "texture bake" or "render to texture" if I good understand

Any experience / suggestions in approaching this activity?

Comments

  • Triem23Triem23 Moderator

    If you're taking the geometry of a high-poly model and applying it to a low-poly model this is called "Normal Mapping.*" (And it's one of the new features in HF4)

    Which 3D software are you using? There's a whole bunch of ways to go about this depending on the package.

    *Ok, Picture a tabletop. The table is our polygon. Imagine a line perpendicular to the tabletop, pointing up into the air. This line is the "Surface Normal." In this case the normal is defined AS that imaginary line, and it's this normal that's used to determine which was a poly is facing for lighting purposes. "Normal Mapping" takes the normals of a high-poly model and maps each axis to a different channel (R, G or B) then combines the channels into a single image. The Normal Map is then applied to the low-poly version so the computer can more-or-less shade it as a high-poly version. I say more-or-less because it's a rendering cheat. If you have a low-poly spaceship with a normal map on it, if you do a super-close "Hull-Scraping" shot you're going to see that the details of the geometry aren't really there.

  • edited March 2016

    I did know about normal map, but I'm confused about the whole bunch of map possibilities (normal, bump, displacement, transparency, illumination...). If normal map is enough good to know!

    To add some questions: such a map is applied to a texture or to the object itself? Also where UV map come in the game? I need an UV map? UV map is automatically generated applying a texture?

    The model is coming from a scanner, zapping between various free and demo programs such as Meshmixer, Cinema 4D, 3d-Coat, trying to define the workflow to achieve the result with min costs.

    Reading about texture bake I did download xNormal and MightyBake, of course I didn't obtain any result having not a good understanding of what I'm doing...both of them output a monochrome image that I suppose it's not the needed map :)

  • Triem23Triem23 Moderator

    I can't answer all of these because some of this is out of my experience. 

    Let's talk about maps in general. With the exceptions of Diffuse and Normal Maps,  all maps are usually greyscale images. (BTW, this also applies to image maps being used in effects like Parallax or Atomic Particles and it also applies to Keys and Masks and Mattes--a Key, Mask or Matte is really a transparency/opacity map map!) 

    In all greyscale maps black is zero/minimum effect and white is full/maximum effect. So, let's talk about map types. 

    Diffuse maps are the "paint job" for the material. This is why Diffuse Maps are actually full color. 

    Specular maps determine where and if Specular highlights appear. Black is no specular, white is full specular. 

    Bump maps are similar to Normal Maps in that they are used to simulate surface details. In a bump map 50%gray usually represents the "actual" surface. White areas are "raised" black "recessed." Bump maps are useful because they're actually easy to draw and can often be added by drawing over an existing diffuse map in photo editing software. Bump maps predate Normal maps. 

    Normal maps we've talked about--a Normal map is basically three greyscale maps in one file, except tge Red channel is X, Green is Y and Blue is Z. 

    And that covers the maps available in Hitfilm. To discuss some maps Hitfilm doesn't support (yet). 

    Displacement Maps are similar to Bump maps except they actually deform the mesh, not just fake shading. 

    Transparency maps determine opacity. It's name sums it up. 

    Reflection maps determine if the material is reflective. Again, it's name sums it up. 

    Illumination maps are similar to Specular maps except we're determining if the model is effected by HDRI lights. 

    UV maps are a special case. A UV map is determined by placing "seams" in a model like you were slicing it open then spreading it flat like sheets of paper. It's converting the surface geometry into X/Y co-ordinates like a pixel image. X and Y were already being used for model position data in 3D space, so U and V were used. UV mapping needs to be done before any other type of map (except Normal) since the UV map is what's telling the software that this pixel affects that polygon. 

    As to your questions if maps affects the model or texture, well it's kind of both. In general a model will be one or more meshes. Meshes can be assigned materials, and these materials procedurally define the look of the mesh. Basic Diffuse/Specular colors, Shininess, Reflectivity, etc,  . Depending on your 3D software you might actually have massive procedural tools that can generate these beautiful animated, multicolored textures. This type of material is often specific to the modeller and only saves in the software's native format--these advanced materials don't save in the 3DS LWO or OBJ files and cannot transfer to Hitfilm.

    Maps modify the textures as described above. Finally the UV is rewrapped so the flat image is mapped to the geometry. At this point a Displacement map would warp the geometry, then Normal map apply. The other maps are processed and the object is passed to the render queue. 

    Now in Hitfilm a 2D asset layer (image, video, plane, grade) or hitting top of the layer stack triggers the render queue. 

    Anyways I am not familiar with your specific tools. General advise: ask @Aladdin4d and @Stargazer54 or @Spydurhank or @NxVisualStudio about tools to do Normal mapping. You can do that at anytime. 

    Then look up tutorials on UV unwrapping for your tools. That's the essential skill. Everything else is painting. Note for simple objects there are basic UV maps predefined. Plane, Cube, Sphere, Cylinder. 

  • @davide445 - I'm no expert in map knowledge but @Triem23 really helped me understand a few things with his explanation above. Thanks T23! Take a look at this tutorial on Displacement and UV Sculpting when you have the time. It helped me design the space station in the second vid below. I also designed a few space ships using this method. Not sure if that's what I'm going to go with in the end (for a project) but I think the process works fairly well.

    https://youtu.be/VY9vHdwUo98

    https://youtu.be/hZJMPIvpebY

  • edited March 2016

    @Triem23 @StormyKnight thanks for the useful info.

    Focusing on the normal map you think I did need to create an UV map? I did understood from T23 normal is an exception. Also apart the tool I'm testing what can be a fast and easy toolset?

  • Which scanner you use, I used Artec Eva, and the number of tris is so huge, that 3ds max keep crashing when I try to open it. I have 16 gb ram anyway. Maybe you can recommend something else?

  • edited July 14

    This was last year, I used DAVID3 scanner (now HP 3D scan).

    To reduce poly and mesh repair I did find really useful GOM Inspect, free but powerful and with professional tools.

    I did finally give up in baking and simply paint the resulted mesh in 3d-Coat using an original photo of the model.

    I also animated and rendered here the model with results good enough as part of whole activity video I created for the museum I worked with (the whole activity was a dried butterfly scanning, repair, enlarge, morphology edit following specialists advice, cutting, slicing, 3d printing, glue, artistic paint).

    https://youtu.be/-jKTi2bS24w

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