HDR Map reflection too large?

[jiggymoon]

Hi all.

I have a question regarding using HDR maps.

This is my scenario ... I have built a High speed train that obviously sits on some rails. I shot a HDR sphere map over some rails and use this to both light and reflect my scene.

Problem. When I move the train towards the camera, I see movement on the reflection in the train for gal scene geometries, but it appears that the tracks that are on the floor, don't 'disappear' under the train, as you would think they would.

Is this because the virtual HDR sphere that VRay creates is too large and has no real relevance to the position of the train.
If so, how can I get around this. I have tried using a smaller sphere and reflecting it, which kind of work..ish, but is by no means ideal.

Thx in advance, R

[A'nW]

Re: HDR Map reflection too large?

So what I gather, is that you have an HDR backdrop of a railroad track and want your 3d train to look like it is moving along the tracks toward you? This is just my thought, but I think that a world background like that is purposely supposed to be "infinitely" far away, just a background for reflection really. It is not supposed to interact with the scene in the way you are talking about, which, I assume, is to integrate your train into the real picture?
What I would do in this case, is take a normal picture (or video if you are doing an animation), geometry match it to your scene (or camera track for a video), and then composite your rendered train on top of that. You would leave your HDR sphere map in your scene to provide the lighting and reflections only, which is really what a HDR sphere map is supposed to do I think.