Quote - Overall they are the same at catching the light. In theory, displacement could be better, because it generates a larger surface which could catch and scatter more light, but as far as i know poser does not support raytracing with displacement, so it should be the same.

Maybe you meant something different but on the face of it that last part is not true. Poser does support raytracing with displacement. I'm using raytracing in these image, and you're seeing the HDR sky reflected in the sample objects.

What you probably meant is that the per-pixel displacement does not get seen by raytracing rays. But full per-pixel rays ARE SENT from displaced surfaces.

So - a mirror showing these objects might make them appear different. But the objects themselves, which are reflecting other props here, are doing the right thing. Some of those highlights are from the sky via Reflection, some are of my infinite sun light via Blinn.

Both kinds of highlight appear to be missing in some places.

Quote - In the close up it does. But in the distant view i would say the outer two tiles look a bit more blurred than the middle tile, so the situation seems to be reversed, slightly.

I noted that in my other post regarding Vilters' claim that distant objects are better rendered with displacement. This is the opposite effect of the highlights, though. Missing highlights are the result of over interpolating. Extra details at distance are the result of under interpolating - the result of using a single sample as data no matter how many other samples should be included in that pixel due to distance.

It's false detail, though. It's actually aliasing.

Quote - Yes, the word "missing" implies that they should be there in the first place. Missing highlights could be the result from both a smooth surface and a bad map.

Yes it could, but my maps are great. I made them correctly and large.

Quote - But (and i am taking a wild guess here about what you might have done for these examples) if you took a displacement map and converted it into a normal map, the result will always be worse and more blurred as the original map, it cannot be better than your input data. The same would be the case if it were converted the other way around.

I did no conversion of any kind. My maps are procedural, generated simultaneously from Filter Forge, then recorded as large images - far larger than what I rendered.

Whatever effects you perceive cannot be ascribed to bad generating technique, low resolution, inappropriate conversion, or noobish incorrect application in the shader. I know what I'm doing. The differences you see are the result of the technology itself - bump versus normal.

In bump mapping, heights are interpolated and then a normal is derived.

In normal mapping, normals are interpolated directly.

This is a fundamental difference. It is at the heart of all the appearance and performance differences, small as they are.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)