HDR Dome poor resolution
marble
Posts: 7,500
I don't do many outdoor scenes but I am trying one today. When I was using Reality/Lux I could apply an HDRi image to the Reality dome and it would be clear and sharp in the background. With IRay, that same image is badly pixellated and somewhat blurred. How do I get a sharp image? I am using the large HDR files and not the so-called ENV files.
Post edited by marble on
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How large? Is the projection type set correctly in the Image Editor (command in the image picker list)?
Well, it is something like 19Mb. It is called Tropical_Beach_3k.hdr. I don't know what you mean by prjoection type. Which Image Editor - what is the image picker list? Sorry, I'm not following you at all, Richard.
I got the HDRi from here: http://www.hdrlabs.com/sibl/archive.html
The image picker list is the menu you can acess for picking an image, or loading a new one, to the left of the slider/colour bar for a mapped property.
3K would be 3,000 pixels presumably - so about ten pixels per degree around the dome depending on the projection type. Are you using the Finite Dome setting in Render Settings? If so, and if you've moved the camera or dome off-centre, you may be getting a restricted slice of the HDRI.
As I don't really understand the dome settings, I usually leave it a default. So that would be Infinite Dome and Dome plus Scene lights.
As for the camera - yes I'm moving that around - how else would I compose a scene? I wouldn't know how to move the dome though - unless those Dome Orientation parameters are what you mean. If so, no - I never touch those but I do use the dome rotation in an attempt to get the desired portion of the image in shot (always trial and error - pretty frustrating exercise, generally).
As you know, the dome is basically a 360° photograph, warped in a ball around your scene. So when you move the camera around, it is possible this could zoom in on one area of the dome and get your pixelation. You could test this by booting up a fresh new scene, and then render nothing but the HDR background with everything, including the camera, at default. It should take like 2 seconds to render, if even that. That will give you a baseline of what to expect. I don't know Lux, but in Daz, moving the camera around with these backgrounds can cause all sorts of weird distortions. It all depends on where the center of your scene is compared to where the camera is. The further from the center the camera is, the more it distorts and/or pixelates.
It certainly is annoying trying to work with HDRs when they don't show up in the preview scene. You could use the iray preview if your hardware is decent eough. Or, you could turn off the dome background, render what you got, and then make a 2nd render of the dome background by itself. Plus, with no 3d objects in the scene, iray preview will work instantly. That allows you to freely move the camera around and get a good angle. Finally, photoshop the 2 images together.
Thank you for the explanation. I'll try your suggestions - perhaps combinig the layers in Gimp might be the answer if I can get a clean image from the HDR.
..yeah until I can get a GPU with more memory I'm "flying blind" using HDRs as the backdrop and lighting does not show in the vieport unless you are in Iray view mode.
I use the AUX Viewport set to Iray for setting up. I hide it if the laptop stops or stutters when moving things about. I only have an i5 CPU with integrated intel graphics.
The problem with using the Aux Viewport in IRay mode is that - if you are using GPU - it needs the same amount of VRAM as the full render (I think that's true but please correct me if I'm wrong). Thus, if the scene is heavy on textures, polygons, etc. you need to switch out of IRay view mode before you can render. Switching in and out gets tedious.
I don't have a GPU so can't answer that.
from some tests ii tried with that image and hdr file seems that just using the 8k jpeg image was more clear to me than the hdr image was had dome set to finite scale multi 28.35, radius 35 the jpeg seemed to be much brighter than the hdr but was still a little blur to it
All HDRIs are NOT created equal, regardless of advertised resolution.
Nevertheless, that same HDRI rendered using Luxrender looks fine, as do any of the others from that freebie site linked above.
Reality/Luxrender doesn't have dome scaling however, nor finite/infinite so I'm not at all clear how and when to use these features in IRay.
OK - after a little playing with parameters it seems that things can be improved. If I use Finite Sphere for the Dome Mode and I reduce the Dome Radius from 100 to 10 then the resolution improves considerably. I've just done this in an empty scene with a plain cube primitive for fast renders but it looks encouraging.
An odd thing happens when I reduce the radius to 1 as can be seen in this screenshot:
And if I pull the camera back at radius 10, the curvature of the dome becomes obvious. I've included the dome at radius 100 for comparison - note how blurred it looks.
For good resolution you need much higher; 20MB size provides great lighting.
I've got HDRs approaching 400MB, and generally use ones that are 150MB (although less can and does work) or more if I want to see the background.
Leafy Knoll is a 7MB HDR and the night scene 348MB.
And you will see curvature; if our planet was smaller then there would be no argument about the world being flat or not. :)
Actually, the render will use the same assets during the render. Leaving the viewport on iray mode actually *decreases* total render time, especially for animations as it doesn't have to recompile/recache/reload the shaders.
I found that nifty tip on Cath's Youtube page, tested it out for myself, and sure enough it works :)
That's very interesting. I know it decreases render time because I always keep one still render open when I'm doing an image sequence for animations. However, I thought that the VRAM requirements over two open renders would be added together.