Displacement Maps Question

[Jazbee]

Hi

Before I start let me just say that I'm not really a 3D pro, so please show some understanding if my question sounds in any way stupid

Now, here's what I'd like someone to shed some light on:

Normally, from what I understand, displacement maps should work similar to bump maps, which means that in a greyscale image 50% grey is value 0 (flat), 100% white = 100% outward and 100% black = 100% inward. When I apply a displacement map in Blender in behaves exactly like that. All of the ready-made displacement maps I've seen look like this as well, which indicates this is how they are supposed to work.

On the other hand, Octane seems to treat 100% black as 0/flat/no displacement and all other shades of grey as outward displacement height levels, which would mean you couldn't have any inward displacement at all and also most ready-made displacement maps would have to be modified to behave as desired. I did try to play with all displacement options provided, but this the conclusion I've reached so far.

Am I missing something?

[Michael314]

Hi,
I'm also not an expert, but there is this "offset" value. If you set it to minus half of "height", you should get exactly the effect you want.

Best regards,
Michael

[Jazbee]

Thanks for your reply.

Hi,
I'm also not an expert, but there is this "offset" value. If you set it to minus half of "height", you should get exactly the effect you want.

Tried it, but it does distort the geometry to some extent. I mean, I can mostly work with the way Octane handles displacement maps by modifying the images themselves to the desired effect. The only thing is that there is no way of achieving negative displacement (for scratches, crevices, etc.) without expanding the base geometry or distorting it using the offset value. I'm also curious why they behave in this unusual way and wether it's due to my lack of knowledge or indeed due to Octane handling it in this particular way.

[gordonrobb]

There is an issue (in my opinion) in this. It's fine that we have a shift value if the displacements won't work from -.5 to +.5. The problem is that for anything Mir complex than a plane, the shift doesn't seem to un-displace in the same way as the displacement, and this results in tearing often. There was word a while ago that there was an idea how to fix this, hit I haven't seen anything.

[blastframe]

There is an issue (in my opinion) in this. It's fine that we have a shift value if the displacements won't work from -.5 to +.5. The problem is that for anything Mir complex than a plane, the shift doesn't seem to un-displace in the same way as the displacement, and this results in tearing often. There was word a while ago that there was an idea how to fix this, hit I haven't seen anything.

I'm experiencing this exact issue right now. I hope they get this fixed.

[gordonrobb]

Best bet is to bring it up in the Realease thread.