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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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.
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?
If you could find a program somewhere to convert the cylindrical image to a "true" HDRi cylindrical .HDR, then we could test it out. I always seem to run into problems finding an editor, etc. to use with HDRi.
The Cylindrical radio button won't work for HDRi backgrounds.
You can convert the image to .HDRi as you have and then use if as a HDRi sky, rather than an HDRi Planar background. However, the top and bottom of the image will be distorted. Because HDRi assumes that the image is spherical.
I spent some time trying to find a "true" HDRi Cylindrical image on the web for testing, (to verify if there is such a thing - a switch set inside to say it is cylindical - and then to test if it works properly), but I couldn't find one anywhere. (If you can find one, then we can see if it would work)
It seems that convert jpeg to HDRi (planar?) and use it in cylindrical projection is possible. Does it work?
But in that case what should be the sky mode? Automatic or HDRi? because HDRi is related to the images selected in the HDRi tab I think, no?
We see in the dialog below, the choosed image is .hdr, so is it ok? is it the image used toilluminate the sky? so, automatic sky?
I'm going to render it, to see.
From my point of view, that's a pity for Y offset.
One question anyway; About light and reflection, ok for HDRi skies but, about HDRi backgrounds it could be a bit different for reflection because in case of cylindrical projection, jpeg background can be reflected on object facing the camera. It seems that cannot be the case of planar HDRi background which are obviously behind the scene.
What do you think?
The problem about HDRis you are talking about is they are generally low resolution ones, almost unuseable unless to maybe, use it non visible, for light only. Good HDRi sky for 1680 rendering is a 10.000x10.000 and is quite expensive, about 100$.
So an intermediate solution could be to use a jpeg background, convert it to HDRi, which is not exactly the same result, I think, but not so bad, and use it in cylindrical projection, because spherical projection as iRender use for HDRi needs special images to not distort it. Would it be possible to use cylindrical projection instead of just planar?
I spent some time looking at these backgrounds, and at cylindrical backgrounds.
We are putting out a new version today or tomorrow which does a much better job with the backgrounds.
However, Y-offset will still not work for Cylindrical Backgrounds.
The bottom line is that if you want good backgrounds, you will need to obtain high-resolution spherical HDRi backgrounds to use as sky and background.
For some backgrounds you can use planar images and the will work pretty well, but if you want the background to light the image, reflect on other objects and/or work well with various views, then HDRi is the best bet.
Here are some sources of HDRi skies and backgrounds:
HDRI Skies which can be used with IRender nXt are available at:
I tried to modify my background to get the horizon in the center and yes, it works fine.
Anyway, if it works, I suppose you manage Y offset in some way to get this result so, I suppose it should be possible to give a specific value in Y-off parameter for any fine adjustment. Could be helpfull.
Ok Al
I'm sure being able to adjust Y position would be very helpfull.
I send you both background and an alpha transparent rendered image. Don't know if you can use it as foreground to mimic the rendering. I just would like to see some trees behind the scene.
I also want to say that I (and certainly all of us) greatly appreciate how you listen your customers and try to improve your product regarding our needs. That's really not always the case. So, beside iRender capabilities, I will recommend it mainly for that.
Thanks,
You should have received a download link via yousendit. Please tell me if it's ok.
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