Displacement map values

Development Asset Creation
,
1

I’m not sure how Reality Scan decides on the values of a generated displacement map.

Lets say I have a simple object relief that i texture project onto a plane directly above the object.
What value does the exr pixel have that’s closest to the object?
Does it depend on the size of the objcect/plane or just the distance between the object and the plane?
What determines the highest value?
The reason I’m asking is because we’re planing to generate normal maps from the displacement maps for a lot of objects and we’re trying to get a consistent result without eyeballing each map in an image editor. (We’re not using Reality Scans normal maps but that’s a topic for another post :).

Thank you in advance!

2

Hi Christian, this is the answer from our developers:

Let us denote the model that is reprojected from as the source model, and the model that is reprojected to (and for which the texture is generated) as the destination model. Values in a displacement map are signed distances between source and destination model surface, along destination model normal. For a flat plane as the destination model, this would be the distance in the direction perpendicular to the plane. The distances are in the object space of the destination model, so a distance of 1 corresponds to the length of an edge connecting vertices (0,0,0) and (0,0,1) of the destination model. There is no particular limit on the distance.

3

Thank you very much for that reply.

I’m struggling with this sentence:
The distances are in the object space of the destination model, so a distance of 1 corresponds to the length of an edge connecting vertices (0,0,0) and (0,0,1) of the destination model.

Would you mind elaborating on that?
I though about giving you my interpretation first but that might only make things more complicated at this point.

4

I suppose the units will be in the used project units.

5

Let me try making an example to see if I get it now:

Let’s say my source model is a relief that is 1m x 1m, with a height of 1cm. the lowest point of the relief sits on the ground plane.
The destination model is a 1m x 1m plane, 10cm above the ground plane.
Would my highest point of the relief show up on the plane as 0.2 and the lowest point as 0.1?

6

Your Scenario

Source model:

  • 1 m × 1 m relief

  • Height = 1 cm (0.01 m)

  • Lowest point = 0 m (ground plane)

  • Highest point = 0.01 m

Destination model:

  • 1 m × 1 m plane

  • Positioned at 10 cm above ground

  • So its Z position = 0.10 m

Assume:

  • The destination plane normal points upward (+Z)

Compute the Distances

Distance = (Source height − Destination height)

Result

Your displacement values would be:

  • Lowest point → −0.10

  • Highest point → −0.09

I suppose it should be more like this.

7

Ah - I understand now. Thank you so much for that. Very much appreciated.