Adjusting background position

Hi,

I have a 8800x5664 background image I want to use in cylindrical projection for my 1800x1200 rendering.

But obviously there is a position problem, I can only see its sky.

Why isn't it possible to adjust Y-offset in this case?

Regards,

Alain

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Permalink Reply by Alain Bonnefoy on March 26, 2011 at 1:33am

In fact I suppose that lighting results could be strange because of the "black hole" at the top of the tube.

I'm trying to make some tests with different images used as HDR, to see.

In term of light, what's the difference between a true HDRi and the conversion you provide in iRender?

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Permalink Reply by Render Plus on March 27, 2011 at 8:23am

In order to make a "true HDRi" you take three pictures of the same scene - One normal, one under exposed and one over exposed. The normal, under exposed and over exposed versions are then used to determine which parts of these scene create the light. This light intensity factor is stored in the .HDR file, along with the RGB (red, blue and green) values for each pixel. We are able to use that factor to provide illumination for the rendered scene.

When we do the conversion ourselves, we "guess", based on whether you tell us we are looking at a daytime image or a nighttime image which pixels are the light source.

Here is a scene captured with three levels of exposure. The routine which combines these three scenes into a .HDR file is able to determine that the sky and some of the windows are illuminating the scene.