A quick test of V-Ray Next‘s PBR* workflow,
Namely designing materials while previewing them using V-Ray,
Defining the material properties using the new (to V-Ray) Metalness attribute, and using Roughness rather than Glossiness, shows good results IMO.
IES stands for Illuminating Engineering Society, it is the organization responsible for creating and maintaining industrial standards for design and manufacturing of artificial light sources.
In 3D rendering, an IES file or “photo-metric file” is a text file containing a photometric description of a light source’s beam spread , pattern and intensity, allowing for faithful depiction of the light source in 3D renders.
Most modern 3D rendering software support IES lights, that is allow loading IES files into the software and lighting the 3D scene using the light source described in the IES file.
Lighting manufacturers make measurements of their light fixture model’s physical light output and create IES files available for download on their websites.
This allows architects, lighting designers, and interior designers to download the files and realistically visualize the light sources effect on their projects.
CG artists use IES lights to add realistic spotlight beam patterns to their renderings and animations, such that can’t be created using regular simple 3D light sources.
Examples of IES lights rendered with V-Ray for 3ds max:
A VRayToon node that creates a graphic contour effect on the rendered image.
A flat shader that uses surface luminance data to define color areas.
* A VRayLightMtl can be used for that.
Creating the VRayToon node:
Click the Create V-Ray Toon button in the V-Ray toolbar to create a VRayToon node.
In the VRayToon node attributes, set line thickness, color, and more graphic properties.
* if you created a VRayToon node and it’s not selected RMB click the Create V-Ray Toon button in the V-Ray toolbar and choose Select VRayToon node.
* To delete the VRayToon node, select it and press Delete.
Creating the toon shader:
Create a VRayLightMTL node as the object’s surface shader.
Create a Ramp texture node, connect it’s output color to the VRayLightMTL’s color input and delete it’s accompanying 2D placement node.
Create a surfaceLuminance node and connect it’s output to the Ramp node’s V Coord input.
Optional remapValue node between the surfaceLuminance node and the Ramp node to clamp the luminance values.
Optional floatMath node to scale or manipulate the surfaceLuminance output value.
Software: 3ds max 2019 | V-Ray Next | V-Ray next GPU
In V-Ray Next (4) for 3ds max, a new Metalness parameter has been added to the Reflect parameters of the VRayMtl material.
This allows for easy creation of realistic metal materials and also effectively enables a PBR workflow with V-Ray.
When the Metalness parameter is set to 1.0, the material becomes completely reflective, the Diffuse color controls the general reflection color, and the Reflect color (which should generally be set to white) controls the reflection color at grazing incidence angle.
The IOR parameter still controls how fast will the main reflection color (set by the Diffuse color) blend into the Reflection color, and I don’t know whether some form of complex Fresnel has been implemented or if it’s just a dielectric simple Fresnel blended over a reflective surface.
An account of the drastic measures that need to be taken in order to ‘persuade’ Arnold for Maya to render refractive caustics.
In the refractive object’s shape attributes,
Under ‘Arnold’, ‘Opaque’ must remain checked.
* This is unintuitive but when refractive caustics are calculated there is no need for transparent shadows. the caustics pattern is in fact the light refracting through the object.
The refractive object’s aiStandardSurface shader must have it’s Transmission layer active.
For a colored refractive object, Transmission Weight should be 1.0,
A color should be selected, and the density of the color should be controlled with the Depth attribute (higher values make the color less dens).
In the shader’s advance attributes, check ‘Caustics’.
In the shader’s Specular layer, set the IOR to match your material.
* The default of 1.52 is the IOR for glass, and water would be IOR 1.33 for example.
For refractive caustics to be rendered, the light source must be an Arnold Mesh Light,
And in its shape attributes, under Light Attributes ‘Light Visible’ must be checked.
In many cases, in order for the caustics pattern’s intensity to be correct,
The ‘Indirect Clamp Value’ must be raised in Render Settings > Arnold Renderer, under Clamping.
In some cases the Transmission value under Ray Depth in Render Settings > Arnold Renderer must be increased for the caustics to render properly.
* Light simulation must be able refract through all the relevant surfaces.
To increase the caustics render quality, the number of Diffuse samples must be raised in Render Settings > Arnold Renderer.
* This may be unintuitive, but the caustics pattern is actually part of the Diffuse rendering of the surface upon which the caustics are appearing.
In the Render Settings > Common tab, choose EXR as the output file format.
In the Render Settings > AOVs tab, open the drop-down menu on the right side of one of the AOVs in the list, and choose Select Driver.
This will bring up the defaultArnoldDriver node Attributes.
In the defaultArnoldDriver node Attributes, under Advanced Output, check Merge AOVs.
In the Render Settings > Common tab, set the output file format, and in Metadata, set Frame/Animation ext. select an option that isn’t Single Frame.
* This will make the Frame Range settings available.
Set the Frame Range.
Set the Maya UI to Rendering and choose Render > Render Sequence.
One of the features I would really like added to the Cycles Renderer is a photo-metric workflow.
That is the ability to set light sources intensity using real-world photo-metric units, load IES photo-metric data, have a physical daylight system, and set photographic camera exposure and white-balance for the output image.
While Cycles currently doesn’t have a fully functional photo-metric workflow,
It is equipped with some important basic ingredients needed for the development of such a workflow.
One Of these features is the Black-Body color conversion node that allows specifying color by Kelvin color temperature,
Another is the procedural Sky texture featuring Hosek / Wilkie and Preetham physical sky models, that can also be controlled according to global position, date and time with this addon.
Recently I’ve had a pleasant surprize finding out that Cycles actually has another important feature for a photometric workflow, and that is that Cycles Area Lights maintain a fixed general light output (‘Luminous Flux’) while area is changed and changes specular intensity correctly to so that the smaller the light source area, the greater its brightness (as it should physically be).
* This in difference to the way a mesh light with an emission shader behaves where the light output is per area and therefore increases or decreases when changing the shape and size of the surface.
This makes designing light sources with a fixed total output of light yet different shape, and therefore different specular reflection, shading, shadow softness possible,
And is in itself a valuable feature in realistic light source design.
* Especially coupled with setting the light color using Kelvin color temperature (Black-body node)
The only thing missing is the an ability to specify the total output of the light source in Lumens (lm) units.
I have encountered a mentioning of Cycles having a physical scale conversion ratio here:
Marco Pavanello, the developer of the Blender ‘Real Camera Addon‘ wrote: “In Blender the Emission Node Strength is measured in W/m^2” I haven’t had the time yet to seriously find out how that should be translated to intensity in lumens..
* It should be noted that both the Cycles Area light and mesh light use the Emission shader as there source for intensity / color settings, but differently,
You can see in the demonstrations below that for a light source of the same surface area a significantly larger strength value is needed to produce roughly the same light output as the light mesh and this is probably due to the output being internally divided by surface area which is in fact the subject of this post.
Here are some renders to illustrate the point, and the diffrent behavior of light mesh (mesh with an Emission shader)
I’ve added a rough glare effect that depends on float color intensity to illustrate the way the specular highlight intensity increases as the area of the ligt source gets smaller while overall light output is the same:
Cycles Area Light with different sizes but same strengthCycles Mesh Light using an Emission Shader with different sizes but same strength
Cycles Mesh Light using an Emission Shader with different sizes and strength changes to compensate
Adobe Bridge is very useful for browsing media in a CG \ Animation workflow,
mainly because it displays thumbnails and previews for EXR files, something that Windows Explorer doesn’t do, and also because it has cool batch functions like loading files as layers in a new Photoshop document and so on,
But I encountered a behavior that can be problematic,
The software uses caching for the thumbs and filmstrip preview in order to display the images faster,
And in some cases where you render updated files with the same folder structure and same names, Bridge will display the older preview images from it’s cache even if you manually deleted the whole folder structure prior to re-rendering!!
I stumbled across this issue when browsing render tests being confused as to why Blender rendered images with old settings, I naturally thought Blender was to blame (I tend to think that a media viewer can’t be the problem because it just displays images..) and looked through the render setting trying to understand what went wrong,
Eventually I found the cause of the problem in Bridge,
And there’s a simple solution with the command: Tools > Purge > Purge cache for _______ folder
But you still have to be mindful that you might be seeing old renders, otherwise you won’t perform this important action.
