Tackling unrealistic materials

It is worth noting that the following is a full version of an article I have recently contributed to. Please have a look at the 3D World magazine(i.e. issue 141)for more in-depth tips.

Although lighting, rendering parameters, composition, camera, post production, etc, are great contributors in the process of producing appealing and photorealistic images; textures and shaders are ultimately one of the most important aspects of the entire process.
It is common for artists to slightly neglect this vital stage, and rely mainly on the subsequent steps (i.e. lighting, rendering parameters, composition, camera, post production, etc...) in order to produce a decent image.
The fact is, once the textures and shaders are competently and meticulously tweaked with, the remaining steps (i.e. lighting, rendering parameters, composition, camera, post production, etc...) will mainly enhance a bare but already realistic 3D scene.
Reputable production companies often use real photo references to emulate real life materials and their physical properties. For best results, the photo reference/s is/are commonly brought into the 3D program, to closely compare, match colours, shadows, lights, etc).

It is a common mistake for artists/studios to begin the work in Max without the slightest idea about the art direction and the final quality desired.
A bad combination of texture colours can at times make a realistic render look unappealing.
It is very important to source for references and “miss /match” colours that will complement one’s 3D scene. A very good source for colour references is a Book entitled “The color scheme bible”, by Anna Starmer.
After carefully observing photos for references of texture/s, colours, scale patterns, physical scale relationship with other objects in the space, etc; the next stage is to bring the photo reference/s to a 2D program (i.e. Photoshop, etc) and “doctor” with them to fit perfectly on designated 3D object/s.
It is worth mentioning that the 3D objects’ scale relationship with one another has to be correct (i.e. door height= 2m; eye elevel= 1.65; human height= 1.70m; etc). Our eyes can inexplicably detect scale discrepancies when existent, therefore perceived unrealistic.

When texturing in Max, it is also a common mistake for artists to assign high resolution textures (i.e. photos taken) of small parts of a big area which are not representative of the entire surface.
This process may result in users having to tile the UVW parameters time and time again in Max.
Then, to eliminate the tiling patterns users mistakenly copy over and over the same texture in a large canvas in Photoshop, followed by blending them seamlessly.
This malpractice often results in a loss of numerous important details such as dust, scratches, AO on the edges, subtle dirt, etc; that often contributes to the realism of a 3D surface.

Production companies avoid tiling the textures as much as possible.
For instance, if the film Director’s intention is to realistically map a detailed old door; they would normally take a “straight on” photo of a similar door (i.e. with no direct light/direct shadows); change the original texture as necessary in Photoshop to fit one’s desired colour; paint new details; omit undesired ones; etc; followed by assigning it directly onto the desired 3d surface.

This technique not only eliminates the tiling patterns realistically, but also preserves all the small important texture details such as dust, scratches, AO on the edges, subtle dirt, etc.

One can still apply very subtle yet visible discrepancies as above mentioned on “pristine” visuals, to add realism to the final image.




The shaders to which the above mentioned photo real textures will be applied into play a crucial role in finalizing the 3d model/s.
The following list will highlight some of the key properties these shaders should have:

Bumps/displacement: Bumps and/or displacement bitmaps play a crucial role in enhancing the textures. In order for its values to be noticeable on the renders, users are required to have enough segments on the 3D object. Again, using photos as a guide will help find the adequate value for the desired bump/displacement.

It is worth mentioning that when lights are added in the 3D scene, its values are often tweaked further to react realistically to the lights.

Round corners: The "round corners" function chamfers sharp edges of 3D objects.
As most objects in real world are somewhat chamfered, the usage of this function is utterly imperative.
To input the correct “fillet radius” value, artists often create in Max, a “dummy” chamfered geometry(i.e. chamfered box from extended primitives) of a similar size to one’s object, and tweak with its fillet values to preview the results of the “round corners” affect on the surface, in the Max viewport.
Since its results are only visible at render time, this trick was adopted to prevent possible artifacts, usually caused by excessive values.

Glossy highlights: Glossy highlights play an important role in making a render look appealing. Most striking photos contain glossy highlights, so the usage of “relative Intensity of highlights” should be a must.
Moreover, its correct value is dependent on scene’s lighting setup; dynamic ranged images being used in the scene; etc.
It is also worth noting that this function works independently and in conjunction with the main material parameters rollout.
Finally, it also helps to highlight the “rounder corners” Parameters.

Reflections: Reflections are utterly vital in making a render appealing. Having a great high resolution environment bitmap and an interesting 3D scene to reflect on, will certainly help improve the quality of the renders.

It is common for highly reflective objects to lose their original colour/texture. This is a natural phenomenon.However, it is not often appreciated by clients. To help override this physically correct phenomenon, users often enable the “metal material” function. This function essentially helps maintain the diffuse colour/texture whilst reflecting the environment. Alternatively, to use glossiness without reflections, one can simply enable the “highlights+FG only” function.

Note: For complex glossy highlights and/or reflections, also plug the bump or displacement texture (i.e. greyscale) into the "glossiness" toggle of “Reflection” group parameters.

Depending on its appearance on the render one may choose to Invert its colour in the "Bitmap" "Output" rollout. This 3Ds Max function is covered in the "Converting a Vray Max scene to mental ray" article, in this blog.
Alternatively, some production companies also use a separate grey scale bump or displacement texture with less contrast. And/or mixed with other proprietary procedural materials.

Also, to further control the amount of reflections on any given surface, one can also use the “custom reflectivity function” from BRDF rollout. This function works in conjunction with the “main material parameters” rollout.

To prevent artifacts on glossy reflections users should focus mainly on increasing the Fast Glossy interpolation density to “1 (same as rendering)” or higher. If necessary, also use the global “glossy reflections precision” and “Glossy refractions precision”.

Finally, it is also worth pointing out that rendering images of size lower than 3500 pixels may cause the renders to look slightly grainy, independently of the high shader settings. To prevent this, simply render at 3500 pixels or higher. One could later reduce proportionally its original size, in Photoshop; if required.

Colours: In addition to using Photoshop to correct colours;etc, it is highly recommended the usage of a shader named “Composite” or “color correction”. “Colour bleeding”;excessive reflections; GI and/or Final gather can at times change the original colour/s of textures in the render.
Its powerful functionalities will help rectify most colour problems. Furthermore, this shader is often plugged on top of the original shader's diffuse toggle .

Note: While some shader developers may disagree with this methodology, the fact remains that not everything that is physically accurate looks photo real and/or appealing.
From my personal experience in the industry(i.e. in the "trenches"...), I have had to tweak with Physically accurate colours and properties of a shader in order to satisfy the Client; Art Director and/or the Director of Photography...whose input subsequently made the image look 100 times better for it!
Besides, even a real footage is treated in post...to a great extent.

So it's great that these helpful functions/tools are now available/accessible to the masses...directly from Max.

Furthermore, the materials’ “indirect illumination options” function values will help emulate the apparent physical properties of an object (i.e. these values can be positive or negative, depending on one's desired effect).

Again, While some shader developers may disagree with this methodology, the fact remains that not everything that is physically accurate looks photo real and/or appealing.

So it's great that these helpful functions/tools are now accessible to the masses...especially when you consider that the FG is "an approximation". ...to aid users with less rendering power.

Rendered elements and Postproduction work: Rendered elements and Postproduction work often help to enhance and address final touches of the previously rendered materials. Some of the most common rendered elements are “reflections”, “Z depth” , “object ID”, “AO”, “refractions”, multiple elements of “matte”, etc. It is also worth pointing out that rendered elements increase the rendering times.

The two images below depict the importance of using professional photo references in order to competently apply all the techniques mentioned earlier.

The first image below was the photo reference supplied by the client; and the second image below was the final render I have managed to produce while at GMJ design.

Photo reference supplied by the client

Final rendered image produced while at GMJ design.

Note that, although the scheme was similar to the above photo reference, some of the textures/colours and design were changed at the client's request. I was instructed to capture mostly the "lighting colour" and "mood".
I had used some of the earlier photo references as guide for the physical properties of most objects in the scene (i.e. chairs, wall, glass, etc.).

I hope you have found the final result interesting.


3D World Magazine



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3D Realism:Practical & Easy Workflows