Author Topic: texture tutorial please!  (Read 8329 times)

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Offline fario

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texture tutorial please!
« on: March 25, 2014, 01:42:33 am »
hello,

I would love someone to explain to me how to fix it.

Someone might make it a little tutorial?

Thank you in advance.

Antoine

Offline evilmaul

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Re: texture tutorial please!
« Reply #1 on: March 25, 2014, 02:14:20 pm »
well u re using a box projection there which basically comprised of 6 planar projections....and given the mesh and that particular texture you get seams. (in some cases box projection is forgiving but definitely not in this case)
you best create some UV projections in whichever model software you are using ..or other softwares like headus UVlayout  and then use UV projection in Keyshot instead of box projection


Offline fario

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Re: texture tutorial please!
« Reply #2 on: March 26, 2014, 12:36:36 am »
hello and thank you very much for your response.

I knew that the projection box was not optimal for organic models.
Here is a screenshot with UV projection mode.

There are still errors.

another thing: circles texture become elliptical ... is it ok for a UV projection? transform what is round ellipses?

I'll test repair software which you have spoken.

The ideal would be that Keyshot in the future, do the repair itself.
« Last Edit: March 26, 2014, 12:38:16 am by Antoine »

Offline TpwUK

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Re: texture tutorial please!
« Reply #3 on: March 26, 2014, 01:20:08 am »
UV mapping is a tricky beast to master. If your model has been imported directly from the 3rd party app like solidworks or via a translator such as STEP import, then KS will be in charge of the UV mapping whilst it translates the models geometry in to a 3D polygon mesh. If you have imported OBJ or FBX or other mesh based formats then the UV co-ordinates should have been set by the application that created them. Polygon Modelling apps that save polygon mesh data tend to have onboard render engines and UV editing tools built into them. The textures or materials you create within that app should be able to be exported and can then be used by KS using UV Mapping method ..... I think

Martin

Offline DriesV

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Re: texture tutorial please!
« Reply #4 on: March 26, 2014, 01:32:04 am »
Simply setting projection type in KeyShot to UV coords using the same set of textures isn't going to cut it. :)

What Marco talks about is UV unwrapping of polygonal models. However, looking at your last image and the wireframe, it seems that you're dealing with a CAD model. By its very nature it can't be 'UV unwrapped' in a straightforward way.

By setting projection to UV coords, the texture is mapped onto every single NURBS patch that your model is comprised of. KeyShot then uses the UV coords of those NURBS patches.

I would look into Marcos suggestions. However, this will require poly modelling.

Dries

Offline fario

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Re: texture tutorial please!
« Reply #5 on: March 26, 2014, 01:43:25 am »
the conclusion:

For CAD designer (not polygonal modeling) Keyshot can not alone achieve good results projection textures pictures on their models ....

??
« Last Edit: March 26, 2014, 01:46:24 am by Antoine »

Offline DriesV

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Re: texture tutorial please!
« Reply #6 on: March 26, 2014, 02:00:06 am »
For these type of models and these sort of textures, you will always run into texturing problems... no matter what rendering app.
It's a 'problem' inherent to CAD models.

The only solution I see is through a new procedural texture.

Dries

Offline TpwUK

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Re: texture tutorial please!
« Reply #7 on: March 26, 2014, 02:10:16 am »
Not at all Antoine. If your cad models are built on regular geometry such as spheres, rhomboids and and the likes thereof, then KS can handle them perfectly well.

Adding things like fillets can cause problems because of the way the NURBs surfaces are stitched or joined together, where mesh densities suddenly change and create seems as can be seen in the mesh you originally posted. This is where zebra modes come into play with NURBs modelling and the 'surface continuity'. If you are using a NURBs modelling package that supports zebra mapping mode, then give it a go, and you will see. Zoom in and pan around the zebra map on your model. If you see steps or breakage in the flow, then you need to refine your model to bring the pattern back or as close as possible so that the result is smooth and logical. Once you have achieved that, then KS will be more than upto the challenge.

Polygon modelling is slow and cumbersome on some kinds of modelling but is by far a lot better for doing 'Organic' shapes where the modeller can adjust points and insert extra loops and edges where needed to reduce the effects of stretching and smoothing things as required. Once the base mesh is sorted then that mesh can be further divided by using Sub-Division algorithms to achieve better quality surfaces that can compete with NURBs mesh densities.

Martin

Offline fario

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Re: texture tutorial please!
« Reply #8 on: March 26, 2014, 02:14:05 am »
ok

I send you my CAD model to test.

Is there no miracle there no software that could repair and direct UV on this type of model?

The competition is launched! ;)

Offline fario

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Re: texture tutorial please!
« Reply #9 on: March 26, 2014, 02:48:38 am »
Quote
If you are using a NURBs modelling package that supports zebra mapping mode, then give it a go, and you will see. Zoom in and pan around the zebra map on your model. If you see steps or breakage in the flow, then you need to refine your model to bring the pattern back or as close as possible so that the result is smooth and logical. Once you have achieved that, then KS will be more than upto the challenge.
thank you for this very informative explanation!

The zebra mode in my software seems correct.

I think it is for export. Obj, that is the problem.

Offline TpwUK

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Re: texture tutorial please!
« Reply #10 on: March 26, 2014, 03:20:46 am »
Indeed the continuity is good, but your wireframe posted shows the stitching and stretching - The stretching by the way is visible in the zebra pattern, so the question that needs answering is whether the model was imported into KS via a plugin, or did you save the model as STEP, or did you save the model out from the creating app as OBJ or other poly format. Then you can narrow down where the problem of conversion is occurring.

The sad fact still remains that NURBs do not translate very well into polygon mesh data and that complex organic shapes really do need to be poly modelled. Now that Groboto (http://www.groboto.com/v3/index.html) has been married into Modo we have something that's really very close to the perfect Poly/NURB hybrid modelling package. Blender is free and can be used to edit the OBJ file, but Blender is naughty in the way it strips UV information from the imported mesh and uses its own technique. From what I hear, you can now edit and export as OBJ directly with no loss, but if you try a test render then Blender will still do the dirty deed of removing your UV mapping co-ordinates.

If you are on Mac OSx then i highly recommend Cheetah3D for poly model editing and basic modelling

Martin

Offline DriesV

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Re: texture tutorial please!
« Reply #11 on: March 26, 2014, 03:21:35 am »
Zebra stripes have nothing to do with UV mapping!
It is merely a curvature analysis tool for CAD.

I've made models in CAD with many surface features (and thus many NURBS patches) with 'perfect' curvature continuity (no kinks in zebra stripes). Yet, when imported in KeyShot cannot be textured with UV coords.

Dries

Offline TpwUK

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Re: texture tutorial please!
« Reply #12 on: March 26, 2014, 05:12:38 am »
You are correct Dries, and i have made the point that zebra is for surface continuity and that anything of a complex nature such as fillets and organic shapes will not translate very well to polygon data. The reasoning for bringing in zebra stripes was to point out that if you have poor continuity, then you will have an even harder time trying to edit the mesh exported out.

Antoine, i notice you are using OSx or linux in your other thread where you have posted video .... I am intrigued with the modelling package you are using, what is it called please. It looks as if it's poly modelling and then you are applying a smoothing algorithm ready for export, if this is the case then the exporter or the smoothing from that app could be the problem.

Martin
 

Offline fario

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Re: texture tutorial please!
« Reply #13 on: March 26, 2014, 05:33:03 am »

the software used is called: 3Design CAD ​​is a software jewelery.
I'm working on MAC

Its strength: it can model polygonal, and then translate the model into a real solid!!

It's really fantastic!
Later you can export this model. sat or. stp and achieve true boolean nurbs!

Here is my demo.


http://www.screencast.com/t/DKFZhzSh

sorry if this post is off topic

Offline fario

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Re: texture tutorial please!
« Reply #14 on: March 26, 2014, 05:34:57 am »
Martin?

Martin W???

:)

I also work with Cheetah and would like to know if this software could ... repair UV imported models.
« Last Edit: March 26, 2014, 05:44:47 am by Antoine »