[Micha]

@Mihai: I feel the same, the beta make the downscale trick much better than the alpha. I'm very happy about this effect in the beta now.

An other aspect: it is a little bit strange, the background emitter is absolutly noise free and the material not, so it looks not like a photo. Should I wish more noise for the emitter.

[Kabe]

deesee,
they mean:

HDRI: High Dynamic Range Image
Images having more than 8 bit-per-channel depth. (usually 16 and 32)
HDR, EXR.... (and now MXI)

LDRI: Low Dynamic Range Image
Images having 8 bit-per-channel depth. (usual images we all use)
BMP,TGA,JPG,TIF...

... HDR images are preferred for illumination purposes.

Well, I hate to be nitpicking, but the difference between HDR and LDR is not just the number of Bits/Channel. If an image is 16-bit/Channel, it can be an LDR image or an HDR image. Some HDR formats (Radiance for instance) use a mere 4 Bytes per RGB-Pixel, which takes the same space on the harddisk tahn a LDR-PICT.

The real difference is the span between white and black, to put this shortly. An LDR image has a dynamic range of max ~8 f-stops, while an HDR can have 20+. As an f-stop means a dupliation of light, this differences is quite obvious.

LDR images are used to be viewed, while HDR images are either viewed in special applications or used for capturing the complete light in the scene.

MXI should be able to capture the real thing, which is HDR. Working for one of the leading HDR photographers in Germany I can assure you that the difference is quite obvious.

Kabe

[deesee]

Thanks Mihai. I won't make the mistake of calling an MXI an HDR ever again.

But where are my manners...Micha, did not mean to hijack the conversation. Your image was so impressive, I just had to know what you were all talking about and how you did it.

[tom]

Kabe, you know I can't give a complete lecture here.
Of course, those bits are about white-black range, otherwise why do we need them
Also know that MXI is far beyond HDR and even it's more than 64 bit.

[Micha]

@ginosso: I understand your problem. I'm not sure my use is the perfect way, but it looks approx. like it should do it. I will make a test with an archtecture background, than we will see what is happen. I feel, my log-lat format HDRI is good for a spherical use, because the image map show distortions at the poles, so that it could match to the uv distortion of a sphere. I don't, which format we should use instead. Sorry, english is not my native language, I hope you can understand me.
Diameter: This is not so easy. I use since a very long time HDRI spheres with Rhinoman|AIR and I have got good solutions with a sphere 5...10 times bigger as the scene. The best for the lighting would be, if the sphere is extrem big. For the DOF it is better, the geometry is like in the real world - if the HDRI show a room, use the size of the Room. Is the sphere to small, than the lighting of a plane table surface is not uniform, you can see the glowing surface around.
An other diameter problem is, that the viewangle of the camera should show the right area (I will call it field of view) of the HDRI. Is the sphere extrem big, you will get sometimes only a small field of the HDRI. The reason for this camera-sphere diameter dependent view is, that camera and sphere don't use the same center. So, you could set camera and sphere at the same center and not the scene in the middle. Maybe, this could be better. I think, I will test it with the archtecture HDRI (uffizi).

You HDRI questions are not stupid. It is an interesting subject and you find not so much literature about the usage. I'm curious about the discussions and tests in the future.

The next step after the HDRI sphere could be the composite work like here: http://www.blochi.com/gfx/hdri/ Maybe, some body will start to try this.

@Desesee: "Micha, did not mean to hijack the conversation" - I'm not sure what you mean, my english is not so good. But, if you want to know more, let us talk about it.

[Micha]

OK, here some news. The half sphere image seems to be only subtle better than the full sphere, so I stay at the full sphere in the future (all my HDRI are full spherical). The full sphere was with 136 polygons, the half has used less.

Also, I have tested the uffizi HDRI. Here the rendering. The colums on the right side show a light distortion, but I'm very happy with the result at the moment. Important for a low distortion: camera and MXI sphere use the same
center.

My experience with AIR was, that only a sperical mapping to a box and a frontal view on a side of the box bring the lowest distortion.

Here a link to a HDRI link collection. http://www.rhinoman.com/phpbb2/viewtopi ... light=hdri For my test I have used the uffizi from the link list. At the www can be find two different uffizi HDRIs, one of them show strong distortion, - the good one is in the link list.

[Micha]

... and here in the classical kitchen environment.

[Mihai]

I don't see no links

The uffizi one looks great, but I have only found a probe for it, not in spherical map....

[Micha]

Upps, I have edit my message with the link.

Yes, probes must be converted. HDRShop do it, but cost much for commercial use. The unfinished HDRShop clone HDRIE should do it too. http://www.acm.uiuc.edu/siggraph/eoh_pr ... h2002.html

Here my converted and darker LDRI from the probe for the MXI viewer for some tests.

[Jake256]

Currently there is no way to convert directly a "usual" hdr to mxi format. You have to first convert your hdr images to a ldr format such as bmp, then convert that to mxi with mxiviewer.
.

What is this mxiviewer? I have a bunch of high-rez HDRI's, some that I have made myself for use with some of my other rendering software. I would like to convert a couple of them, but I don't understand the mxiviewer thing. I'm on a mac. Is this a windows only thing. Did it come with the beta? I would appreciate it if someone could point me in the right direction. thanks

[Micha]

In windows world the Maxwell viewer is the render window that show the rendering. I don't know, how maxwell it do.

[MetinSeven_com]

Hi guys,

I've been away from active Maxwell usage for a short while. How can I convert a HDRI to MXI for use with Maxwell?

Thanks and cheers,

Metin

[Micha]

Open a LDR image in the Maxwell viewer (the same like the render window), change intensity and gamma and save it as mxi.

[Jake256]

Open a LDR image in the Maxwell viewer (the same like the render window), change intensity and gamma and save it as mxi.

The only way I can get the window open is to do a render. I'm on a mac using the lightwave plugin. How do you open the viewer without a render? i don't want to seem stupid(probably too late for that).

[Mihai]

The viewer is part of the Maxwell package, you should be able to open it separately, without doing a render...I don't know how it is on a Mac, I assume you have program folders You should find it in Maxwells program folder.