Getting shaders to work on imported .obj [SOLVED]

Comments

• Leana Posts: 12,735

  November 25

  Is the model UV mapped?
• Silas3D Posts: 727

  November 25

  3D models created in STL or other print formats often don't have UV maps, which are required to apply a shader successfully to a model.

  If you're not familiar with what a UV map is, briefly it is an unwrapped version of the models surface, which can then be used for creating textures which are then applied to the model as a material, and this material would only work for that model.

  Shaders are different in that they are typically a repeating pattern that can be tiled as appropriate on a surface, but there is still a dependency on having a UV map for the model.

  Rather than risk overwhelming you with how to check for and create a UV map (which would require other software such as Blender) I'll give you a simpler solution that will work without said UV maps :)

  With your model selected in the scene, go to the Create menu in Daz Studio menubar and select Create New Iray Decal Node.

  You can just click accept on the following dialog, then do the following:

  1. With the decal node selected in your scene, go to your Parameters tab and select Decal in the list of properties on the left (at the bottom)
  2. By default, Clip Mode is set to Position. Change this to None. This will ensure that your shader will cover the whole model without worrying about positioning it.
  3.  Go to your Surfaces tab and select the Front surface, then apply your desired marble/granite shader
  4. Et voila!

  This uses a technique called projection mapping, which literally projects the shader onto the model - much like an IRL projector onto a wall. As such its not constrained by the target models UV.

  You haven't attached a photo so don't know what kind of model you're working with, but there are limitations of this technique.

  Depending on how flat/curved your model is and position of your camera, you may need to tweak the projection rotation settings. Bear in mind this is not the general rotation settings, as decals have their own.

  Hope this helps and isn't too confusing!
• Vargr Posts: 31

  November 25

  Hmm, fiddling around a bit.

  It seems some other shaders (from DimensionTheory) do work (and some others), but the mainpart of those I have do not.

  So the problem seems to be related to the shader I guess.

  I need to find a good "Shaders 101" that can explain the workings for me.

  I guess my problem is solved or at least answered.

   
• Vargr Posts: 31

  November 25

  @Leana:

  I very much doubt the figure is UV mapped coming from a .stl-file.

   

  @Silas3D:

  UV maps: I see, good explanation.

  I will try the steps you gave and return.
• Silas3D Posts: 727

  November 25

  Bear in mind that some shaders have projection mapping built into them, sometimes they can be referred to as procedural as well.

  The vast majority in the store will depend on UV maps though, and this is the industry standard.
• Vargr Posts: 31

  November 25 edited November 25

  The pictures might take a while to be ready - sorry.

   

  @Silas3D:

  Below is the figure in Texture Shaded display, imported from the .obj-file, opacity set at 1, rotated and scaled.

   

  Picture 1: http://gofile.me/6nfX6/EeYMLkuzg

  Your steps were easy to understand and follow - thank you!

  And I do get the result I want. Somewhat.

   

  Picture 2: http://gofile.me/6nfX6/Ejt7g8iPU

   

  As you can see, the stone texture does get applied, but only partly (for instance, the backside of the harp is all white'ish as is the inner part of the coat, etc. Perhaps the figure is too complex (too many polygons)?

  Question: Why is the selector box for the decal node off set from the figure?

  Again, thank you for your help!

  Post edited by Vargr on November 25
• Silas3D Posts: 727

  November 25

  Ah yes your model is quite complex but that's the beauty of projection mapping, it works with any 3d mesh. The backface issue is probably because there's another setting that needs to be enabled on the decal. Can't remember exactly what it's called off the top of my head, but somewhere there's a drop-down that is by default set to front and there's an option for front and back. Don't worry about the selector box, that's just the bounds of where the physical decal node is in the scene. Providing you changed the clipping setting as mentioned previously, it shouldn't affect the projection, but it wouldn't hurt to check the transform settings of the decal and set them to 0 if currently non zero value.
• Vargr Posts: 31

  November 25 edited November 25

  And I am back from business elsewhere.

  You are correct, it was - with Iray Decal Node selected - Parameters / Decal / General / Face Mode --> Front and back

  Now the shader is uniformly distributed. Very nice looking - and it accepts any Iray shader I have tried to throw at it.

  As far as the selector box - I can get it positioned so it more or less is at the right spot (but the height of the box and the height of the figure is different). However, regardless of where I place it it works, so I will not be bothered by the off-set now that I know it doesn't matter.

  Thank you very much for your help!

  I really appreciate it!

  I learned a lot through this and will put the procedure into my OneNote with all things Daz :-) 

   

  Post edited by Vargr on November 25
• Silas3D Posts: 727

  November 25

  No problem, glad it worked for you :)
• Richard Haseltine Posts: 107,880

  November 25

  Silas3D said:

  Bear in mind that some shaders have projection mapping built into them, sometimes they can be referred to as procedural as well.

  The vast majority in the store will depend on UV maps though, and this is the industry standard.

  or they may not need any kind of positonal data, or they may use acvtual location in space, etc. It's true that most mateials on store products need UVs, but there are various ways they might not.
• Vargr Posts: 31

  November 26 edited November 26

  I have tried to make a step-by-step instruction for those coming here with the same question:

  Steps to undertake for Daz 4.23: Import Import the wanted .obj-file through File / Import Add Iray Decal Node Select the imported object in the Scene tab. In the Create menu find and click Add New Iray Decal Node. Select the Iray decal node in the Scene tab. Go to the Parameters tab and select Decal in the list of properties on the left. By default, Clip Mode is set to Position. Change this to None. This will ensure that the shader will cover the whole model without worrying about positioning it. Go to your Surfaces tab and select the Front surface, then apply your desired shader. Et voila! If the shader does not cover the object completely, try this: Again, select the Iray decal node in the Scene tab. Go to Parameters / Decal / General / Face Mode and change it to Front and back. The bounding box for the iray decal node seems off The bounding box for the Iray decal node might seem off-set in relation to the object it belongs to. This has no impact on how it works, so this off-set can be ignored. If it bothers too much try to adjust the transform settings of the decal. Setting them to zero should help.

   

  Again, thank you to Silas3D for helping out.

  Post edited by Vargr on November 26