3D Rendering

In the next tutorial I will try to explain what parameters you need to control in order to obtain realistic caustic effects with 3ds max and vray.

Open the “caustics start” scene that you will find in this zip file.
As you can see, the glass material is already prepared:
-reflect 213:213:213 with fresnel reflections checked.
-refract 238:238:238
-IOR 1.44
-Affect shadows – checked

First, go to the “Vray: caustics” rollout and activate it by checking the box next to it.
If you render it at this stage you will end up with something like this:

The caustics effects are already visible but they have a fake look and lack definition.

The most important parameter that we need to adjust is the “caustics subdivisions” that are emitted by the light. For this, you need to right click on the direct light, choose vray properties and increase the “caustics subdivisions” from 1500 to 20000 and render it again.

The caustics are starting to look more real.
Now let’s see what other parameters do…

If we change the “search distance” parameter to 0.02 we will end up with something like following:

As it can easily be observed, smaller values produce much sharper caustics but a lot more noisy.
Higher values result in smoother caustic effects, but at the same time the higher the values, the blurrier they get.

After several tests, I am happy with a search distance value of 0.09 for this scene. The caustics still look a bit noisy, but we will try to adjust this by tweaking the “max density” parameter.

Max density is probably the trickiest parameter, and if you don’t understand how it really works, you can end up with unexpected and undesired results.

First, let’s do a test; increase the max density from “0” to “1” and look what happens:

Where did all the caustic effects go?
Take a look at the following diagrams:

If max density is greater than “0”, when vray needs to store a new photon, it will look if there is another photon within the radius specified by this parameter. If it finds one, it will just add the energy to the one in the map, in order to keep the photon map at a smaller size (case 2 of the diagram). If the area is too large the end result will look like there are no caustics in the rendering.
If no other photon is found within that radius, the new photon will be stored in the photon map (case 1 of the diagram).
After doing some tests, I think that a value of 0.002 works just fine for this scene.

In order to realize just how tricky this max density can be, leave it at 0.002 (that works fine at the moment, as seen in the rendering above) and increase the caustics subdivisions of the direct light to 50000 and run another test rendering.

You would expect better results, right? WRONG! The result looks exactly like the one with max density set to “1”. Basically by increasing the caustics subdivisions we ended up with more photons acting like “case 2” of the diagram.

Other parameters:
Multiplier – it makes the caustics brighter if increased, or less bright if a value lower than “1” is assigned to it. In theory you should leave it at “1” since it is supposed to give physically correct results.

Max photons – somewhat similar to “search distance”, but instead of using the distance between photons to interpolate, it uses a higher or a lower number of photons.

Mode – works almost like the irradiance map. You can choose “new map” to calculate it again, or you can save it once you are happy with it and load it later for further renderings.

Another important factor to keep in mind is that the looks of the caustics depend a lot on the geometry of the objects that cast them. For example if you want to render a swimming pool with caustics you need to model a realistic water surface (or at least a really good displacement map), otherwise it will not look natural.

I am pleased to announce that the kitchen 3d models collection is published on Premium3dmodels.com. It contains over 120 3d models suitable for using in kitchen renderings.
All the models are correctly scaled and are accurate representations of real life objects.
The level of detail of every 3d model is high enough even for the most extreme close-up renderings. As usual, the models come in 3ds max (version 9) format, with all the high resolution textures and vray materials included.

This collection is split in 2 main categories:
1) Kitchen appliances – contains a large variety of microwave ovens, gas ranges, kitchen hoods, mixers, blenders, espresso machines, dish washers and more.

2) Kitchen accessories – all the accessories that you may possibly need to populate a kitchen scene (utensils, pots, dish racks, kitchen knives, recipients, sinks, dish trolleys, graters, peelers, egg slicer, garlic press, recipes book, and more).

The entire collection is priced at 119 usd, but if you purchase it before 25th of February, you will benefit from a 30% discount.

I invite you to check it out, and if you have any questions, don’t hesitate to ask.

First of all, since I haven’t had the chance until now, I want to wish you a happy new year, all the best and many projects and opportunities in 2010.

I’ve just came back from my winter holidays and while browsing through some arch viz forums I’ve stumbled upon the short video done by Alex Roman (Jorge Seva) and I must say I am absolutely amazed.

This is really a master piece, and with no exaggeration, probably the best cg animation I have ever seen, and I am not talking only about architectural visualization.
The guy obviously has a lot of talent as a movie director, stage designer and photographer besides the fact that he truly masters the software.

Although I can not stress enough how much I like it, I can’t help but wonder how this style would work from a commercial point of view. From my experience, every time I try something more “artistic” it doesn’t go well with the client. Even a small depth of field effect used to focus on some elements makes most clients ask me “Why 70% of the rendering is blurred? Is it a software error?” I have even had problems explaining to some clients why the white walls look bluish in a dusk rendering. Although a small part of our job as architectural illustrators is to educate the clients, sometimes we have to consider the fact that time is money, so instead of spending it explaining this and that, just give them what they need and that’s it (as long as it still looks at least “ok”, of course).

I am curious what you think about this, and even more curious if you managed to get a “sign off” doing something a bit more “different”.