Ground Projection: Corona vs. V-Ray

[^Lele^]

We surely qualify workloads differently, you and I.
Alas, i made my points at best i could, you made yours.
Someone else will decide.

p.s.: you mistake a "high horse" stance for limited resources, and take my intent at debate so to make a wish actionable for petty gating.

[Stefan_Laub]

Lele it seems really you are just not from Archviz industry, i understand your arguments from your perspective, but from other needs, like mine, one need the projection in that way distorted, as corona (or Vred, or octane) does it, (so the content isnt strangely distorted looking in many cases)
i see no other way to explain it. i have 20+ years experience in archviz render and i know what i am talking about too.

the really easy solution(i guess also technically no drama) woudl be to just offer BOTH solutions for the different uses, and not make vray unneeded complicated.
(not adding a needed checkbox is not always the best solution i think, - i know you guys what to keep the gui uncluttered)

[^Lele^]

Have you ever tried the cameraMapPerPixel map?

[Stefan_Laub]

whats really not what i needed or meant, Lele,....
i tried to explained it above.

all is about easy of use in end

[^Lele^]

Well, Corona's projection is that which i mentioned, minus the controls (as explained above).
I have not yet seen evidence of the workflow being any good (unless your stuff hits the defaults, it's quite a bit of fiddling.).

So i find no merit in spending resources on something which is inferior to what's already there, and proven to be working for the same amount of workload on the user's side.

To make it trebly clear: It's an opinion, and has no influence on what will eventually be developed or not.

[JonasNöll]

Hi, as a V-Ray user that just gave the Corona demo a 60 minute tryout, THAT was the first thing that jumped into my eye.
That's the reason why i started this thread. Just the possibility to put a car in my hdri without the background being completely distorted was a major eyeopener.
I mean I get the point that some people prefer to have the hdri infinitely far away and don't care about distortions and both ways have their advantages and disadvantages.

So for someone who for example just wants to put a car into an HDRI and use the HDRI also the background with minimal distortions without having to use backplates can you explain how you would tackle this in V-Ray in the way that you would recommend everyone should use it?

[^Lele^]

Camera projection on the geo you wish to use of the spherical pano, or simple UV mapping of a spherical probe to a sphere will give you all the options you need.
If you find that workflow lacking, and producing a case impossible to attain without the mapping mode Corona has, fine.

But then i'd rather the user had ways to automate (f.e., like pick a camera to link to. Or a node centering option.), rather than spinners and IPR to get the thing properly aligned.
I'd *much* prefer to have a new node type which dealt with all of these issues, rather than having the stuff scattered around between texture settings, max system dialogs and light nodes.

And that's what bothers me the most: once we delve in what is essentially camera mapping territory, the options will baloon to no end, while essentially covering twice the ground Max has already successfully tackled (successfully, but not without twenty+ years of painful, production-driven refinement. Which we'd have to start anew.).

[kosso_olli]

I have not yet seen evidence of the workflow being any good (unless your stuff hits the defaults, it's quite a bit of fiddling.).

I give up, sorry. There are images right at the start of this thread, there were links posted to additional topics with images as well.
Take any model of a car, put the HDRI in the environment with ground projection enabled. You will not get a decent result.
In Corona you do the same, value for camera height is the height of the capturing device on set (mostly between 100 and 120cm off the ground), adjust radius until the projection matches in size. Bam, you're done. Is it really that hard to see the benefit?

Look at the first image in the thread. See the size of that Nissan Micra in the V-Ray version? It is massive compared to the Mustang, while the ground is matching pretty well. In Corona, you can control the size above the horizon. Hence the correct scaling of the Micra and the reflections in the car.

[^Lele^]

I've shown you it's not the projection, it's the settings (radius, in fact, ought to be renamed "height". no, really. Try it, you'll see.).
Perhaps a controllable blend radius around the horizon would ameliorate the distortion issues when the camera and ground projection settings do not match?
It still wouldn't "fix" what you perceive as wrong, but it'd be more tolerant if the user wished, at the expense of some precision.

Truly, if all you need is a squashed sphere, though, you should model one such asset and set it up with some rigged controls, so to be able to reuse it as you see fit, with many a probe type and many a common scenario for your workflow.
On top of being custom, it'd also have a ton more usability in that it could be parented around, and centered around nodes, included in trace set and so on and so forth.
And use the domelight for what it was made: light.
This is however truly a matter of personal preference.

p.s.: what exactly were you referring to, about VRED's projection modes? I looked and found nothing special, have i missed anything?

[Pixelcon]

Didn't vray a few versions ago decide to become more user friendly by hiding controls and whatnot? Not everyone wants to deal with rigging, parenting objects, dealing with trace sets, and the rest. I just want something that does what I need it to do. I open corona and I want to render an object in an HDRI and corona does it. Vray makes it a chore. You above mentioned that Corona requires "...quite a bit of fiddling" to solve this 'problem'. I think you have got it wrong. Vray is the one that requires all the fiddling. Unless you have done this operation before, it's not possible to get right first go without googling and visiting the forums etc. And even then I end up saying 'fuck this' and using Corona instead because it's either too hard to do in Vray, or it's not even possible. Vray needs to be a swiss-army knife and to be ready to do what I need it to do. Today. Right now. Not after spending half a day twatting around testing and asking on the forums for help.

Can we at least have a basic tutorial then? No wonder Corona was such a hit. You don't need years of experience to carry out something that should 'just work'. I think if you cannot carry out an operation intuitively alone, or without a simple tutorial which is easy to find then something needs to be fixed.

[JonasNöll]

Lele, could I send you the scene file and you can just demonstrate how to do this the most simple way that you recommend users should do in this case? I just tried a bit but somehow wasn't able to get anything convincing projecting it on a half dome spherical geometry, so would be interested to see which approach you are recommending in this case. I am honestly just interested to see what is the solution for this, so as long as it works I'm fine. If the solution is userfriendly is another debate, but for now I would be just happy to have any solution at all

[^Lele^]

You can find a ton of tutorials on the internet.
Or use Corona.

[JonasNöll]

You can find a ton of tutorials on the internet.
Or use Corona.

Hmm, if I'm not missing something this tutorial just says: "Increase your ground projection radius", which doesn't give any satisfying results at all.

[kosso_olli]

Glad I'm not the only person with this issue. For years it seemed nobody had the same problems.

Regarding Vred, take a look at these screenshots. It is capable of projecting the HDRi onto cubes and stretched spheres, which for some environments works quite well. You can even animate the projection to get convincing motion blur. Please have in mind that these are not used for the directly viewed background, as that would be a corresponding photo taken on the same set. These are entirely for getting correct reflections in relation to the background. Something V-Ray can not do, without the hassle of work you recommend. Vred and Corona can do this out of the box.

Really interested in your approach to this as well.

[^Lele^]

Sorry, how do you do this with Corona on a box?