Cineversity

Hi All

Im fairly new to texturing.I have a two part question.(using r23)

Currently trying to bake out Glass material
I am using a bake material tag with transparency and reflectance selected but i keep getting a black image see below.
I have a sky with a HDRI in the scene also (to get the reflection) I’m trying to create a ‘fake’ glass material for A.R
Is there a way to do this? I know it takes like 5 seconds on blender.

Also is there a way to have an alpha background on the bake material tag I can only see colour options I just want one with an Alpha.

Any help would be appreciated.

Hi finance,

Often the results of the surface will change when the situation is altered. The object itself moves, the camera point of view changes or the context’s content is different over time.

I really need a scene file to see what you like to have in the end. Please just zip the file and attach it here (max 4MB), or I can share a Dropbox upload link. (Dropbox, Google, Amazon, Apple, Adobe, or Wetransfer are the only ones I will touch for security reasons.)

If it is just the overall transparency of an object, why bother to bake it? It would be just a single value map based on the amount of transparency. A variation or even the total refraction amount can’t be baked in Cinema 4D with the Texture bake tag.

Glass has refraction, and the result inside of a scene can’t be baked in, as it requires the current constellation in AR.

Similar to that is refection; if there is no variance in the reflection’s strength, then this will also result in a single value gray-map.

The reflection itself is also in need of the AR’s current situation; otherwise, it will look like painted on.
If that doesn’t matter, the reflection will be taken as if the surface would be the camera, polygon by polygon. Otherwise, you have to enable the “Use Camera Vector”.

The Background Alpha, not to my knowledge directly, you would use the Background (Attribute Manager> Bake Texture> Tag>  Background Color and use anything that is not given on your object. Besides, check the UV option to on and set the background to blue, then use this to create what you need. The UV islands will be green, the UV-borders red, and anything else will be blue; an easy channel picks what you need. But make certain the blue is not showing up on your backed material. If I would know more about why you need that Image background alpha, I might be able to explore it in a better way.

You certainly have looked into this:
https://help.maxon.net/r23/en-us/Default.htm#html/TBAKETEXTURE-ID_BAKEOPTIONS.html#BAKETEXTURE_CHANNEL_UVMAP

Please let me know if you like to share the file. I’m happy to look into it and, in the same way, to send you an upload link.

All the best

Hi Dr Sassi

Yeah if you send me an upload link i will share my file with you.

Not just the transparency but the look and refractions/reflections, the A.R software is web based and does not allow for shaders (annoyingly) there is no other way of producing the look that i want.
A colleague of mine managed to fake it using blender he was able to bake the glass texture out.

I will attach a photo of the results my colleague got from the web A.R maybe that will help and his baked results i’m just trying to mimic it in C4D for my own workflow.

Hi finance,

Yes, that looks pretty wrong, given that it is for AR.

I am happy to have a look at your file! Take a glass with water and move it in front of your eyes. You will see what I mean. If one can’t move with AR, what’s the point?

Have you disabled communications? I can’t send a PM to you.

I will leave this link for an hour in the forum. I will get an email when the file arrives. Please save it with assets.
(…) Thanks - I got the file.

Cheers

Hi Dr. Sassi

Thank you for taking a look. Yeah I understand the need to have reactive refractions.
I’m uploading it now.
I think its just a limitation on the programme I’m using it seems to be the best work around.

If you have any better work arounds that I could try that would be great to know too, but there is no glass material just a transparency and without the added polish it just looks like its a plastic cup.

Thank you for your time and help I really appreciate it.

Hi finance,

Here is your file back. Please let me know when you have downloaded it, as I can’t send you a PM. I will stop sharing it soon.
(Let me know when you are online, I am not certain if that needs to be kept private)

I have taken the polygons out that are not needed and optimized the UV, using the full texture.

I placed six cameras around the object and took from a distance a shot. I would shoot the same way a practical object for modeling to avoid parallax. Yes, that is a long lens, but at that distance, the field of view is very close to a parallel projection.

I camera projected the image back and had a hand-drawn alpha for the overlap. Which resulted in this image; see below.

The reflection I took just from the Sky object. The HDRI image had a lot of dynamic, but if you shoot those for yourself, safe the result always in Open EXR, 32bit/channel. EXR 16bit/channel is fine; even it has only 18 stops of precision, and around 10 stops a little bit less so. Enough for anything I have shot in the past two decades in HDRI. Avoid radiance at all costs. (It is like jpg compared to raw.) Nothing that should be used ever in production.

Having said that, I used a small bit of depth for the delivery here and used a small colorspace as well. You might do better.

The whole process would take a lot of time to explain, but below, you find a link (in my signature) about shooting and camera-mapping/projection. Perhaps make a tutorial request. I do not say that so often, but here, the complexity was just too much to give a full run-down. Besides, I will try this evening an more simpler idea. I hope that is better and faster.

BTW, I place an X in the Material Tag Selection to switch the tag off. The X could be everything that does NOT resemble a selection’s tag name.

Again, this is all wrong in refraction and reflection, but for an app that can’t produce it, it is perhaps the best we can do.

ENJOY

Hi finance,

So, thinking about getting the most reasonable fake of this static refraction/reflection, I followed a different idea.

This is truly based on the Glass and perhaps will not work for other objects.

There are two techniques that I have mixed that might lead to a relatively fast and perhaps easy way to get your texture.
The techniques are based on the Cylindrical “Lens” and baking context with an object.

The Cylindrical “Lens” was introduced one to two decades ago, based on a request of Digital Matte Painter. Long story short, it can be set up as a 360º camera with a vertical axis. The start of the idea here was to place this “camera” directly in the Glass’s rotational axis. This allows looking through the glass in a nearly objective way. In other words, none could see it that way, but all views averaged might come close, something like that.
I did not feel that this was the end of it.
So I placed a cylinder around it that reflects on the inside. It does so with 2048 polygons, not smooth, but straight. So always pointing toward the center axis of the glass. Hence the 2048 pixels wide.
The vertical axis is used to increase, or degrees the pixel-amount, based on the Cylindrical “Lens” would now look through the glass into the Mirror Cylinder. This means that the Context, the Sky, would not have a huge influence anymore. So, the Compositing Tag is used to see the Cylinder, but the Rays, etc., will not, and in that way, the rendering will result in a more reasonable result.

Once rendered, I would use only the Glass then, not the filling nor foam.
The effect of projecting this rendering onto the glass itself is more convincing than the two other elements that were used during rendering.

In short, the Cylindrical “Lens” looks through the glass (filling and foam) allows the context to be rendered, but the Cylinder allows for some more information from the surface of the glass.
This rendering is projected in a cylindrical way onto the glass. Done.

One scene file has the render set up for the texture. The other one the Glass with texture.

Again, plausible fake. Perhaps a mix out of both (six cameras/Cylinder) allow for enough information to create this fake.

Enjoy