A nice feature of Vue is the possibility to add dispersion effects for materials with a non-zero refraction index. Dispersion is the result of the fact that the refraction index of a material is dependent on the wavelength of the light.

We all know this effect from a prism where white light is dispersed into rainbow colors, but also the sparkling of diamonds is caused by dispersion.

In real life, what is usually called white light is a continuos spectrum of all wavelengths depending on the properties of the emitter. This is called black body radiation in physics. The perceived color varies with the temperature of the radiation and the properties of the sensor. Bright sunlight appears white to us and corresponds to a temperature of about 5500 K.

Now you might think that the “spectral” atmosphere settings of Vue will reflect the physical properties of sunlight.  But if you create a scen with a prism, you will notice that white light (and all other colors) in Vue is treated as a mixture of red, green and blue light, as represented by the RGB values you can set in the options dialog for the light source. So in a way, the “spectral” name for atmosheric effects is a bit misleading.

The type of the light source does not matter for this effect. A spotlight acts the same as the sun or a point light. Thes types only differ in the way shadows are created. The special feature of the sunlight only is that it influences the sky and cloud colors, but the calculations for these effects also rely on the RGB values instead of a black body spectrum.

For most purposes, this “fake dispersion” does not really do any harm, as the spectrum usually is squeezed together so much that the RGB nature of the light can’t be detected. But if you want to do closeup renders of optical effects, you will hit the limit of realism that can be achieved with Vue.

This is a followup to my comparison of Vue lighting models for an outdoor scene. Because lighting for indoor scenes is much different from outdoors, I am covering this topic in a dedicated post.

I set up a simple indoor scene, just an empty box with a few geometric primitives in one corner. Walls and floor are flat white, the ceiling is blue. Just as in the outdoor series, I made two variations of the scene. Again, all renders were made at a 640 x 480 resoulution on “Final” render level

1. Closed Box With a Single Point Light

Closed Box - Standard Model

Closed Box - Radiosity Without Boost

Closed Box - Radiosity boost 4.0

For a closed box, Global Ambience, Ambient Occlusion and Global Illumination models are useless because they involve the influence of the sky on the objects.

You can easily see that Global Radiosity is a must for indoor renders. It is also advisable to make use of the boost slider as the results will look even more convincing.

2. Box with Indirect Sunlight Through a Window

Indirect Sunlight - Standard Model

Indirect Sunlight - Global Ambience

Indirect Sunlight - Ambient Occlusion

Indirect Sunlight - Global Illumination

Indirect Sunlight - Radiosity Without Boost

Indirect Sunlight - Radiosity Boost 4.0

The first noteworthy result is that Global Illumination works far worse here than Ambient Occlusion although it is supposed to be superior. And it beomes very obvious that even with Global Radiosity Vue has significant problems handling tricky light situations like this one. Even with a 4.0 boost setting there are obvious light leaks around some edges. I also played around a bit with the advanced indirect lighting and photon map settings within the render options dialog, but was not able to get much better results.

For lighting situations like this one, Vue is significantly inferior to unbiased renderers like LuxRender or Yafaray.

If you want to test render settings for this scene, here is the scene file as download:

download: Indoor Test Scene (318.34KB) added: 28/11/2009 clicks: 149 description: Indoor scene for testing lighting models

But beware, the user settings are set to extreme values, so the render time will be long, if you don’t change the settings.

Luminous materials are a great addition to Vue. With these you not only can create interesting night time scenes but also useful microstock-worthy pictures.

I just told you that white is the favorite microstock color. But black has its uses as well. Bright colors just look bettter on a blackground, and by using luminosity you  can further enhance this effect.

While white backround pictures appeal more to the general mainstream media, the combination of luminous colors with black leans more toward technological and youthful topics.

Creating luminous materials in Vue is so easy that you don’t really need a screenshot. Just open the advanced material editor and select the effects tab on the far right. Setting the “Luminosity slider to a non-zero value turns on the effect. Just play around to see what looks good. Also the combination of luminosity and glow can give interesting results.

As an example I included the green glass material from the first picture as a free download.

download: Luminous Green Glass (7.89KB) added: 23/11/2009 clicks: 138 description: Transparent green material with luminosity turned on

In the atmosphere editor of Vue you can choose among five different lighting models. They differ in how the effects of indirect lighting is calculated. I will compare the effects of these models on a sample scene. But first here is what each mode does:

• Standard Model
  A uniform ambient light of pre-defined color is adde to the scene. You can choose how much will come from the sky and how much will come from all directions. Horizontal surfaces will be brightened more by light from the sky
• Global Ambience
  This takes into account the color variations of the sky. A surface facing a blue part of the sky will receive a little blue light, surfaces facing clouds will receive white or grey light.
• Ambient Occlusion
  Every point in the sky acts like a tiny light source. An point on an object receives a bit of shadow if another object is occluding the path to the sky. Only objects within a pre-defined range will cast these shadows. If the path is free, the point receives light from the sky.
• Global Illumination
  This is basically the same as ambient occlusion, but there is no range limit. So all objects influence each other.
• Global Radiosity
  Instead of calculating shadows as in the AO and GI models, the radiosity models asumes that any obect that recieves light will reemit a bit of it according to its physical properties. This light affects the surrounding objects. This is done recursively. Vue includes an option to “optimize for outdoor rendering”. This effectively cuts down the number of indirect contributions because usually in outdoor scenes this effect is less relevant.

Comparision of the Lighting Models

To compare the different lighting models I used a simple nature scene with a basic grassland terrain and an ecosytem of red maple trees. I used two different atmospheres for the test: “Default” for a clear sky and “Glasgow” for bad weather. No other settings were changed. The images are 640×480 renders on “Final” setting with Vue 8 Complete.

Default Atmosphere – Clear Sky

Standard Model

Global Ambience

Ambient Occlusion

Global Illumination

Global Radiosity with outdoor optimization

Global Radiosity without outdoor optimization

The standard model is easily recognised by its uniformly bright coloration. In GA the shadows within the leaves of the background trees are very dark. They lighten up with AO and even more with GI which is unusal according to the manual. GR is almost as bright as the standard model, but the coloring of the leaves is much better differentiated. Optimized GR is a bit darker than standard GR

“Glasgow” Atmosphere – Bad Weather

Standard Model

Global Ambience

Ambient Occlusion

Global Illumination

Global Radiosity with outdoor optimization

Global Radiosity without outdoor optimization

The results here are slightly different than with the default atmosphere. Global Illumination is now noticeably darker than Ambient Occlusion and outdoor optimization for radiosity results in a significantly brighter picture.

Conclusion

The standard model should only be used if render times would get too long otherwise. All other models give significantly better results. Where there is no sunlight, Global Illumination will darken the picture as compared to Ambient Occlusion, with much sunlight it seems to brighten the shadows more than AO. Global Ambience is a good and reasonably fast alternative for scenes without much direct light. Global Radiosity works best in all atmospheres, but I would recommend it only for detailled scenes where objects are close to each other. I don’t think that vast open landscapes will profit much from radiosity. Regarding the difference beween the two radiosity variants, I think it is up to personal taste which version looks nicer. I couldn’t honesttly say that I would prefer one over the other.

For a comparison of lighting models for indoor scenes look here.

I just installed the upgrade from Vue 7 to Vue 8. One of the first things I had a a look at is the new planet feature. Now it is possible to have true planets with spherical terrains and their own atmosphere. In the previous versions there was only the workaround to simulate a planet by using a sphere primitve.

The feature is hidden in the main options dialog. Here you can select if your scene should be spherical or not. If you don’t select “planetary terrains” though, the spherical view will only be simulated. Otherwise you can zoom out and see your planet in its full glory.

The above render is the result of my first quick go. As always in Vue, tweaking parameters will result in even better pictures. But as this is a new feature, it takes some time to fully master it, so I decided to let you know about my first impressions right now.

I have noticed two things that could have been solved in a better way:

1. You are forced to use a spectral atmosphere. I fully understand that a realistic rendering of a planet can only be done with a spectral atmosphere. But I was also hoping for the possibility to create unrealstic toon-like planets. It would have been better that artists could choose the degree of realism that they wish to inlcude in their works.
2. To create the geography of  your planet you are more or less forced into the use of an infinite procedural terrain. This means very high polygon counts and render breaks with “Building procedual terrain…” that are pretty usless most of the time because the camera is usually placed in a satellite orbit altitude where the planet surface basically looks like a map anyway. This becomes very noticeable at higher resolutions.

But still the planet feature is a great addition to Vue and will create a host of new opportunities for great pictures.

A valuable tool for creating impressive pictures for mircostock is DOF (Depth Of Field). By simulating the effects of a normal camera you can add that extra bit of realism to your pictures that make them stand out from the rest.

The impression can be intensified when the subject of the pictures itself is not realistic. My example picture shows a fantasy model of a virus which I created right at the beginning of the swine flue craze.

The use of DOF gives the impression of a look through a microscope into a drop of a virus infested liquid. Using green colors for the picture is essential for the potential to sell. In nature, green is the symbol for a healthy environment. But as far as the human body is concerned, green symbolises sickness and decay. This is simply becasue there is nothing green in an on the human body unless we are really very ill. So a green coloring transports the message of the dangerous threat from viruses better than for example red.

How to Set Up Depth of Field in Vue

DOF is turned on in Vue by setting the “Blur” value in the camera options box to a non-zero value.

It is important to set the focal point of the camera where you want to have the focus on your picture. You can either set it by changing the focal distance in the camera options box, or you can klick on the tiny square at the tip of the line that sticks out from the center of the camera symbol and drag it to the focal point.

Make sure your render options include depth of field rendering. But be warned that rendering pictures with depth of field takes a lot longer than without. Generally, the result will justify the longer rendering time, but when you combine DOF with other time consuming featurs like volumetric clouds, radiosity and materials with subsurface scattering, your picture can take days to complete, if you don’t own a render farm.

Vue comes with a sample scene called “Product Showcase”. This is just a simple basic scene with a white floor and a white sky with a Ferrari racing car. e-on Software included this scene to provide you with a generic setting where you can do sample render of objects or plants that you created in order to sell them or give them away.

Of course you can also use this sample scene to render anything you want if you need a white background.

Floor reflections

The writing is a standard text object. I chose “Eurostile Bold” with rounded bevel and 2.5 extrusion. The floor is slightly reflective, but the reflections look better if the reflectivity is increased a bit. The floor material is transparent with the “Turn reflective with angle” option checked. This is used to simulate some kind of milky glass. Here is the trick: Increasing the “Global transparency” value will increase reflectivity. This is something not very obvious for those not familiar with the physical laws of reflection and refraction.

Text Material

First, the surface of the text object will get a slight shinyness:

The coloring is done with the formula editor inside the material editor. What makes the coloring special is that there is a gradual color change across the whole object. For this to work, you need the AdvancedGraph module or a version of Vue where it is included. To bring up the function editor, choose the “Color & Alpha” tab, right klick on the “Color production” preview and select “Edit Function”

The x value of the “Position on Picture” input node is used to select a color from the default rainbow color map. This colors each pixel of the object according to its x coordnate on the final picture. The multiplier is used to squeeze the gradient a little because there is a bit of margin left and right of text object. Here I used a value of 1.17 for the multiplier.

This is just a fairly simple demonstration what a powerful tool the combination of the function editor with the material editor can be.

Download the Rainbow Material

download: Rainbow Material for Vue (6.56KB) added: 16/11/2009 clicks: 90 description: Colors an object according to its x coordinate on the final picture