How to determine the proper Texel Density for a CoronaMaterial

[bunny]

Hello fellows,

I am very new to rendering, and I decided to go with Corona. I am learning all I can about it right now. One issue that befuddled me is determining the PROPER texel density in an ACCURATE and FAST manner. I open already existing materials in the Corona Material Library and each sample has a number written next to it. I imagine this is a demonstration as to how the material looks on an object of that given size? Can I use this information, somehow, to determine the proper TEXEL DENSITY? I want to avoid adjusting the UV scale manually hoping I get it right. I am attaching an image of what I am talking about.

Any help, advice, would be greatly appreciated.

Kind regards,

[cjwidd]

Don't take this the wrong way - and others on the forum might not appreciate this opinion - but if you are truly just getting started with rendering, I would start in Unreal Engine. I think you'll be able to learn more, faster, with lower cost, less hardware requirements, and those skills will still be relevant for offline renderers like Corona Renderer.

Regarding your question, texel density is often couched in terms of UV scale uniformity, not necessarily the absolute scale or reference scale of a particular texture. Corona Material library contains many materials that default to real world scale while others rely on a tiling number.

[bunny]

I appreciate the swift response. The reason why I went with Corona is because I need a good Product Visualization render engine that provides all the features needed for 3D rendering commercial products (furniture, tech stuff, cars, food, etc. -- ANYTHING THAT SELLS TO CLIENTS). It was either VRay or Corona for me and I went with Corona. I do not imagine I can get the same Studio render results in engines such as Unreal, which are game-centric. All I need are 3 lights, two cameras and a white floor.

In any case, to add onto your reply, those materials that default to real world scale, does it mean that the number shown next to the material should be applied on a sample of that size? Meaning, when I unwrap a model, do I keep the size of the UV shell to correspond to the actual size in 3d space? For instance, a 100cm object in 3d space should have shells that fill the 1 to 1 UV space? since the whole 1 to 1 UV space can be considered to be 1m squared?

[PROH]

Hi. I think 3dsMax & Corona are a great choise for the job :)

You're mixing up things in a slightly wrong way. The number you're showing on the pic., is referring to the physical scale of the object - not pixel density. The same goes for numbers used with "Real world Scale". When using "Real World Scale" both the material and the UVW should be set to "Real World Scale" - not traditional 1 to 1 UV space.

I suggest looking up "Real World Scale" in the 3dsMax help files, to get a better understanding of this, and understand how to switch between "Real World Scale" and traditional 1 to 1 UV space.

Best luck.

[romullus]

For instance, a 100cm object in 3d space should have shells that fill the 1 to 1 UV space? since the whole 1 to 1 UV space can be considered to be 1m squared?

Not really. Real word scale means that 0-1 UV space is corresponding to 1x1 area in 3D space measuring in system units (don't confuse it with display units). So the answer to your question depends on the system units - it would be YES if system units are meters and NO if system units are anything else.

[maru]

Getting back to the original post:

I think this is a misunderstanding and over-complicating things which are really simple.

The number highlighted in the screenshot is just an indication "hey, this shaderball was rendered in this scale, so that's how the material will look in your scene". You do not need to care about it. You can ignore it. We could have even rendered the material library thumbnails with no units whatsoever on a solid gray floor.

Most of the materials in the Corona Material Library are using either Real-World Scale option or Triplanar mapping. This means that if you apply them to your scene objects, the scale will be handled automatically (just make sure that the Real-World Scale option is enabled for your objects, too!).

For more information, see:

Real-World Scale vs Triplanar mapping - https://forum.corona-renderer.com/index.php?topic=20616.0

How to use the Corona Material Library - https://coronarenderer.freshdesk.com/support/solutions/articles/12000039648

Triplanar map - https://coronarenderer.freshdesk.com/support/solutions/articles/12000068417

3ds Max Real-World Scale - https://knowledge.autodesk.com/support/3ds-max/learn-explore/caas/CloudHelp/cloudhelp/2016/ENU/3DSMax/files/GUID-27F58B25-C61E-4658-AB1E-7A6C20B23D1F-htm.html

[bunny]

I want to thank you all for taking the time to clarify things to a newbie. I will definitely look into everything you said and try to get the grasp of things once and for all.