I have a problem with V-Ray HDRI in ground projection mode, placed inside a dome light: Changing the radius parameter has no effect on the parts above the horizon line. It only has an effect on the ground surface.
Please take a look at the three images. Don’t laugh at the teapot, it is real-world car size, as indicated by the wheels. The goal is to show a car parked next to a sidewalk in a city. There is an infinite V-Ray Plane below the car, set to shadow catcher via the button in the V-Ray toolbar. The HDRI in the domelight is instanced to the background slot in the Environment Tab from Max.
By default, the part below is projected way too big, as shown by the big patch of asphalt below the car. Also, the window front behind the car is way too big. So far, so good.
Now, let’s change the radius parameter for the ground reflection. The ground below the car is actually looking very good judging by the street and asphalt, but everything above the horizon line is not scaled accordingly. The background above the horizon is still twice as big as it should be. I can’t understand the reason for this, as it brings up a number of problems. First, the reflections in the car would be wrong, and second there is a severe distortion from the ground towards the background. Because it has to blend from the correctly scaled ground to the incorrectly scaled background.
Is there a way this can be fixed? Is it a bug at all? Basically I want to tell V-Ray how “big” the environment from a HDRI is that I put in the scene. If you need the scene, please tell me.
judging from the screenshot the distance from tripod to the kerb is about a width of a car so 3d camera is too far from the model to look natural. zoom in so you get 3/4 of a car in the frame and it will look better.
The background of the horizon stays at an unrealistic (fixed) size, no matter where I place the camera, also regardless of the focal length. Take a look at the image, I changed the camera and the environment stays the same. First is the most logic one, second and third are zoomed in and out. Notice the background is still unrealisticly scaled, it is the same on all three images, even on per-pixel-level.
Their radius paramater scales the background as well, as intended. Notice what happens when he is zooming in and out. The background scales accordingly.
Does the environment above the horizon scale correctly? I doubt it…
Also, I am not able to zoom in this close, because I need to show the car in its full size. It is not the background that I am after, but more about the reflections on the car. Because they are way too big. All that reflects is basically a shop window, where in reality I should see other stuff as well. I have reference images from a stand in car and would love to show the rendered one for comparison, but I am not allowed to. Reflections are way different, even though the HDRI is taken at exactly the same spot where the stand in car was.
Well, I hate to admit it, but I just installed the trial version of that other renderer, because I had to know how it works there…
As piotruss3333 said, ground projection has it’s limits, but only in V-Ray it seems. The result from the test on the other side of the fence was very good, the reflections on the car are MUCH closer to the reference image of the standin car. Mostly because I am able control the size of the shop windows and stuff using the radius paramter.
If there is something similar in V-Ray that I am missing, I would really like to know!
if it is reflection you are after and hdri was taken from the spot the car was parked in than I guess you should map it to a sphere/dome around the car. in tight environements this offset between object and camera is more noticeable.
but than it’s interesting that another engine is more capable here.
I would love to show some more image to better make the point, but I can’t.
The fact that Chaosgroup stays silent drives me mad. Something I never had before here on the forums.
Well, is this something that could be improved? What was the intended purpose, if not this?
If you need anyone testing this, I would do it without doubt.
This is where the term ‘radius’ for ground projection is confusing… It should actually be called the Dome Capture/Projection Height. It should be a world-unit value. So typically it should be 150cm - 170cm depending on where the dome was captured.
I think an additional Sphere radius or even a rounded-box projection could be very useful for certain situations, Particularly in city locations where there are tall straight buildings next to vehicles… the dome projection does really not work well here and we often have to build up geometry and camera-map textures back on to get reflections working correctly.
That’s what I am doing right now to get it working properly. The reflections are not believable otherwise, especially on black cars where you can see everything. Is quite time-consuming, though.
