OTOY Forums

Hi!

I (and my friend confirmed) noticed strange and very big problem when using opacity maps.
The problem does not occur with VPR so it must be in Octane or Octane LW plugin. It is not related to latest plugin quickfix, it happened also with previous update. We have no information for earlier versions as we noticed this recently.

The problem shows best in image so here is VPR capture which works as it should (four black disks that consist of one polygon and uses opacity mask to clip the object). To use this, just turn off the nodes in DotWall surface and use VPR. Here is the same with Octane IPR (same happens with F9). For this, just turn on the nodes for DotWall surface and open IPR. As you can see, the object with opacity map cuts any objects that overlap it even outside the visible part.
This makes for example plants impossible to make as petals and leaves objects often overlap.

Has anyone noticed this problem or are we doing something wrong? I don't think so because we have tried all possible settings, used alpha channel in color map etc.

The test scene is attached so anyone can try the same

Any comments/ideas are very welcome!

Thanks!

Antti

I can confirm this and it is a ray epsilon thing, if you increase it the lines get even thicker. I suppose this is a limitation of the current engine.

Yes, try to set 0.0000001 as ray epsilon in the kernel node ... it is going to show 0.0, but the internal value is ok.

-Juanjo

juanjgon wrote:Yes, try to set 0.0000001 as ray epsilon in the kernel node ... it is going to show 0.0, but the internal value is ok.

-Juanjo

WOW thank you VERY much for this and even so fast on weekend!
It indeed seems to fix the problem!

Antti

This should be in the manual that 0.0001 is not the smallest amout you could enter. I thought this was the smallest.

BorisGoreta wrote:This should be in the manual that 0.0001 is not the smallest amout you could enter. I thought this was the smallest.

Yes and maybe that setting could be changed to be more realistic i.e. value that will still show in the control
But even value 0 works fine but if I increase it, any scene seems to go crazy so I don't quite understand what that setting really does. Yes I read the manual but still I don't understand the deeper meaning of that

So is it ok to keep it at 0.0000001 or even 0, what problems that can cause and in what kind of scenes/situations?

Anyway, we have now tested that in original scenes and it seems to fix the problem so VERY much thank you Juanjo, once again

Antti

This number defines the scales at which Octane works properly. Similar as OpenGL it can only work properly at some scale range that you define with this ray epsilon value because of limitation of number precision inside the engine ( Octane doesn't use high floating point precision, that's why it can work with consumer GTX cards and not only Tesla cards or TITANs which have higher floating point precision )

This means that if you define a very small scale such as in your case the scene will work fine for objects at the distance from say 10cm - 10 meters. Anything closer than that will show you those lines again ( but you won't go closer because you don't need to show 1/10 of the leaf across the entire screen ). But anything further away than 10m will start to show different artefacts ( often seen as radial circles across the screen )

EDIT: I would also like to be able to edit ray epsilon value and see what exactly it is later ( not to show 0 for very small values )

BorisGoreta wrote:This number defines the scales at which Octane works properly. Similar as OpenGL it can only work properly at some scale range that you define with this ray epsilon value because of limitation of number precision inside the engine ( Octane doesn't use high floating point precision, that's why it can work with consumer GTX cards and not only Tesla cards or TITANs which have higher floating point precision )

This means that if you define a very small scale such as in your case the scene will work fine for objects at the distance from say 10cm - 10 meters. Anything closer than that will show you those lines again ( but you won't go closer because you don't need to show 1/10 of the leaf across the entire screen ). But anything further away than 10m will start to show different artefacts ( often seen as radial circles across the screen )

EDIT: I would also like to be able to edit ray epsilon value and see what exactly it is later ( not to show 0 for very small values )

Thank you very much for clear explanation, now it makes total sense
But yes, the editable value could be internally divided by 1000 or even 1000000, that way it would show up correctly

Do you think having it at 0 is 'dangerous', so it should be >0 anyway?

Thank you again Juanjo and Boris, this Octane (LW) forum is the best forum I have ever joined and of course Juanjo is incredibly fast to answer and usually even fix problems that seem bugs or actually are bugs in no time

Antti

I think 0 is just the smallest value it can work with and you should use it for a very small scale scenes when filming something that is very close to the camera.

This is a pirate ship sail with epsilon 0:
so all sorts of rendering errors

this is the same view with epsilon 0.000008:
looks good

this is with the same epsilon but with camera moved back:
looks bad again

this is with epsilon adjusted to 0.00004:

Thank you Boris, now I REALLY got it, excellent examples!

So basicly for 'macro' images (<10cm cam dist) 0, then if render has problems, increase epsilon until it looks fine.
But indeed, as the values are so small, we need to get the value to be something that is still displayed correctly in LW control, please change that Juanjo

Antti