OctaneRender for Carrara 2.23.0077 [Preview]

Sat Jun 06, 2015 5:10 am

PhilW wrote:There has been some discussion on the DAZ thread about hair strands rendering thicker in Octane than in Carrara for the same settings. Would it be possible to reduce the thickness a little (maybe by around 20%) so that the two match better between the two programs?

There are four thickness bases, thin, medium, large, and very large. They are silly names with no actual dimensions attached to them so I had to eyeball them to begin with. Do you want them all reduced or only specific ones.

Sat Jun 06, 2015 6:25 am

Finally found the cause of the crash. New update posted to this thread...

Sat Jun 06, 2015 7:19 am

Sighman wrote:
PhilW wrote:There has been some discussion on the DAZ thread about hair strands rendering thicker in Octane than in Carrara for the same settings. Would it be possible to reduce the thickness a little (maybe by around 20%) so that the two match better between the two programs?
There are four thickness bases, thin, medium, large, and very large. They are silly names with no actual dimensions attached to them so I had to eyeball them to begin with. Do you want them all reduced or only specific ones.

Hi Sighman, I think mostly I (and other people) use the medium one for human hair so that would be the most important to change. I remember doing tests and think that there is a 10x difference between each level, so Large at a 0.1 setting = Medium, Medium at 0.1 = Thin, etc. So if you change one, you should change them all. Consistency between Octane and Carrara is the main thing.

Thanks for the new update, I will try it later today, I am just rendering an animation at the moment.

Sat Jun 06, 2015 1:33 pm

Yeah - it doesn't crash! Thanks Sighman.

So I have started to play with getting variation in the colour of the hair, and I am having difficulties in getting much contrast in there, like it is (partially?) blending the colours rather than each strand being one colour or the other. I have tried using a texture map with B&W noise, also the turbulence and ridged fractal functions as the control between different colours, but it is not easy. Any tips on how to do it or what I may be doing wrong? Incidently I found that changing the projection to UV was needed to get the colours to go along the strands as would be expected, but this doesn't seem to be the default conversion?

Sat Jun 06, 2015 2:06 pm

PhilW wrote:Yeah - it doesn't crash! Thanks Sighman.

So I have started to play with getting variation in the colour of the hair, and I am having difficulties in getting much contrast in there, like it is (partially?) blending the colours rather than each strand being one colour or the other. I have tried using a texture map with B&W noise, also the turbulence and ridged fractal functions as the control between different colours, but it is not easy. Any tips on how to do it or what I may be doing wrong? Incidently I found that changing the projection to UV was needed to get the colours to go along the strands as would be expected, but this doesn't seem to be the default conversion?

I have had similar experiences. You do need to use UV projection on those shaders that support it if you want strands to have solid colours. I do not have any examples of Carrara shaders that vary the hair color from hair to hair so I don't have any auto convert logic in place. I have asked in an internal thread how the shaders work with hair but I got no response. You might try posting your own questions in the Commercial Support thread.
I am certainly open to suggestions on how to better support UV mapped hair.

Sat Jun 06, 2015 11:41 pm

Hi Sighman, Thanks for the suggestion, I have posted a question in the Commercial Support section.

In the meantime, do you have a way to double check that the UV mapping is indeed working correctly. If all strands have the same UV coordinates (0,0 perhaps?) then they would all pick up the same colour, as is happening at the moment. Even a simple example, such as a plane with an Octane checker pattern on it - that renders OK in Octane, but add hair and use the same checker pattern for the diffuse channel and you get uniform grey hairs, rather than a checker pattern of hair. That is what renders in Carrara's native rendered, but not in Octane, so it is a puzzle!

Sun Jun 07, 2015 6:25 am

Here is a very simple example of uv mapped hair. I used the same octane shader for the sphere and the hair.

Make use you enable UV mapped hair...

: OctaneHair.png (7.48 KiB) Viewed 4929 times

Sun Jun 07, 2015 6:58 am

New update posted to this thread.

Sun Jun 07, 2015 7:58 am

Hi Sighman, Thanks for the test scene, well it certainly works for that, doesn't it! I tried substituting an image map and that worked on that set up too. Now if I could duplicate that for an actual hair model, we'll be away! No luck so far though.

Just to let you know, a couple of times while playing with hair settings, the viewport doesn't seem to have updated, so I clicked on refresh and got a Carrara message "An error has occurred", and clicking on "OK" then closes Carrara.

Sun Jun 07, 2015 9:10 am

Hi Sighman, Please could you have a look at the attached zipped Carrara file. I know the hair is a mess, but it appears to be mapped in one small section of the hair, with the rest a uniform colour. I thought this may give a clue as to what is happening? The UV maps on the head shape are OK, but it does not seem to be being correctly passed to the hair.