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View Full Version : VPR differs from render and additional questions



Sebasvideo
01-06-2013, 09:38 AM
I'm sure this will turn out to be something really lame that I overlooked since I started learning Lightwave a week ago, but I thought that VPR was the only way to work in Layout that would show what the final render would look like. But I'm :bangwall: and :compbeati trying to find out what am I missing in this silly project I started to practice compositing.

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One of the scenes is a giant ball floating over my front yard, with me looking up at it. As you can see in the screen capture, the shadow is not perfect by far, but hopefully in time I'll learn to make more realistic ones. My main problem now is that as you can see the shadow in VPR shows with the color I wanted it to but the final render shows a much darker shadow. I tried to find a tutorial on using the shadow catcher and I didn't find one, so I assumed that the way to do it would be to create a ground plane, position it to match the ground in the footage, apply the shadow catcher node to it and play with the light until I found something that would look more or less decent.

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Since the shadow catcher doesn't have any kind of opacity setting for the shadow, and setting transparency in the ground plane once the shadow catcher has been applied doesn't change anything, the only way I could find to make the shadow look more or less real was to adjust the Shadow Color property in the Lights tab.

I went back and forth for the last couple of hours between settings and the surface editor trying to figure out what's wrong, but I'm still getting the same result. It's like somehow the renderer doesn't care about the Shadow Color property, because even if I set that all the way to white, it will still render the same exact shadow, and if I set it to total black, then the shadow in VPR will look darker than the render. So what am I missing?

A couple more :newhere: questions:

1) Is there an easy way, without 3rd party plugins, to make some kind of energy sphere? Something more flashy than what I did, with like light rays coming out of it?

2) Is it possible to configure the image viewer in a way that if I set the camera to 1080p, when I hit F9 it will show me the full frame at 100%, and even better at full screen or maximized? As you can see in the screencap I'm working with the multiplier set to 50% to render faster for previews, but sometimes I like to see the full resolution, and in that case it renders to a half size window, which I have to maximize and then go to the top and choose 100%, which gets annoying when you have to do the same several times.

Thanks,

Sebastian

Danner
01-06-2013, 03:28 PM
VPR has a few differences with the final render, to get as close as possible untick the "draft mode" (it will get slower) and avoid shadow mapped lights.

shadow catcher tutorial:
http://www.youtube.com/watch?v=njOxE1C-ZVI

Volumetric lights would make rays come out of the energy sphere, they are slow to render tho.

Sebasvideo
01-06-2013, 04:12 PM
Thanks for your reply. I forgot to mention that VPR wasn't in draft mode, as well as full resolution. I'm not sure what you mean by "avoid shadow mapped lights", probably because of my inexperience with the program.

jwiede
01-06-2013, 04:45 PM
I notice that you are viewing the render in "linear" mode in the picture viewer, by any chance do you have CC set to sRGB or similar (iow, anything except "linear")? Setting color-corrected OpenGL "on", combined with a CC display setting other than "linear" would produce results as you've shown. You might want to make sure either display is set to "linear" in the CC prefs panel, or set picture viewer to match whatever color profile display is set to in the CC prefs.

VPR uses whatever CC profile is set in the Display setting, so unless Display is set to "linear" what VPR shows won't match a render in picture viewer shown using "linear" color profile, because they'll be shown using different CC profiles.

Sebasvideo
01-06-2013, 05:56 PM
After checking everything you mentioned I would think that's not the problem, although I know it would seem that way. Color corrected OpenGL was not on, and every possible option for CC was set to linear in the CS tab, so everything matches. Besides, if I had a mismatch between color spaces the difference would be far more than just the shadow; the sphere would also be darker or brighter. For example if I set CC to sRGB in the CS tab, render the frame and see it in the Image Viewer in Linear, everything looks much darker, not only the shadow. If I set everything to Linear on the CS tab, render the frame and switch the image viewer to sRGB, everything looks horribly brighter.

In my case the only thing that changes between VPR and render is the shadow, the rest stays almost the same, although the rendered frame is a little bit brighter. I can tell in the bushes on the right, the shadows in the render show a little more detail, but of course this is far less of a difference than the difference between the shadow in VPR vs. rendered mode.

The main thing here is, no matter what color I set the shadow color to in the shadows tab of the lights tab in Render Globals, it will render exactly the same black shadow. VPR will show the color I choose, but the rendered frame will always show it 0,0,0.

Can it be the type of light, or maybe I should use a square shape instead of a ground plane? I guess I'll try that just in case.

prometheus
01-06-2013, 06:28 PM
I have issues with lensflares behind objects, (doesn´t seem to be color space issues when I tried to switch)
and also volumetric lighting when using opacity, in vpr it looks ok, but if you have opacity values the final render will not show any casted rays.

I need to evaluate that more with some test though.

Danner
01-07-2013, 10:38 AM
This won't help you much on your current situation, but you should know about shadow mapped lights, they can come in handy.

Shadow mapped lights are a special kind of lights in lightwave where the shadows are calculated as images of a defined resolution. This lights are VERY fast, specially if only the camera moves in your scene and you turn on the cache on them, that way they are only calculated once in your whole scene. They also have really fast soft shadows too. This is all configurable in the lights properties panel. The limitations they have are that your lights must be spotlights and they are converted to raytrace lights in VPR, (that is why I told you to avoid them if you want a closer approximation to the final render) Sometimes they can have jaggies or leak if their resolution is not high enough. I use them all the time, they are great time savers for arch-viz flythroughs.