making reflections in poser (part 2)

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section 2: the reflector’s Reflection_Color value

Set the ground plane colour back to red. By default the Reflection_Color is pure white. Try making it black. This completely removes any reflection. Now set the floor Diffuse_Color to blue (RGB 0, 0, 255) and Reflection_Color to red. The reflection is not so bright and is coloured purple (Figure 6)!

Figure 6
Figure 6.

For interest, change the cylinder colour to blue and the ground plane to yellow, leaving its Reflection_Color at red. Although we have just swapped the two colours, the results are not the same, giving little reflection but a red specular highlight (Figure 7).

Figure 7
Figure 7.

This shows that the reflector’s Reflection_Color interacts primarily with the reflector’s Diffuse_Color value; the colour of the reflected object seems to influence the brightness of the reflection rather than its colour (try changing the cylinder colour to quite different colours and the reflection colour is still tinted with the colour in the reflector’s Reflection_Color channel).

So, rule number 4:

Rule 4. The Reflection_Color channel, if set to anything other than white, will dim the reflection and tint it with that colour (unless it is a neutral greyscale colour).

Personally I can’t see why you would ever want to change the Reflection_Color, because the results are difficult to predict. But it could be useful for special effects, perhaps.

Note that this only applies to raytraced reflections. The Reflection_Color is of major importance if you plug a reflection map into this node.

section 3: the Reflect node Background colour

Reset the colours of the ground plane (red, with Reflection_Color at white) and the cylinder (yellow). Now change the Background colour of the Reflect node to white. You can see that the floor turns pale pink but the reflection colour is unchanged. If you try some other colours, the floor surface colour changes but the reflection colour does not. Rule 5:

Rule 5. The Reflect node Background colour interacts with the reflector Diffuse_Color but does not alter the colour of the reflection.

I put this in the same category as the Reflection_Color channel: for the most part, leave it alone. However, there is one useful thing you can do. Suppose you are producing a mirror and and would like some sort of background image to appear in the nirror behind your reflected object. You can't plug an image map into your reflector's Diffuse_Color channel, because this must be set to black to reflect properly. What you do instead is plug the image map into the Reflect node's Background channel, and set the Background channel colour to white. If you do that you will see the sort of effect in Figure 7a:

Figure 7a
Figure 7a.

You can plug other nodes into the Background channel, it doesn't have to be an image map.

section 4: other values in the Reflect node

These are simple. Softness affects the sharpness of the reflection – in other words, turning this up blurs the reflection. Unfortunately unless you keep it subtle the results are not that wonderful. Try it set to 0.5 to see what I mean; instead of a nice soft reflection it looks as if a firework is going off under the cylinder (Figure 8).

Figure 8
Figure 8.

You can improve this using the Quality setting – turn that up to 1.0 and see (see also the much-prolonged render times!). You can fiddle with the render settings – the minimum shading rate and the post filter may improve matters – but not very noticeably.

Rule 6. Using Softness needs to be done carefully and subtly.

The Quality setting affects the number of samples taken by the raytracer when rendering the scene, and should improve the accuracy (and therefore the quality) of the rendered image. In practice it doesn’t seem to make that much difference except to the render times, which can be significantly prolonged.

Rule 7. Use Quality sparingly as you may see little difference to the image at the expense of long render times.

The RayBias setting is an odd one. Try setting it to 1. Note how the reflection seems to become disconnected from the object (Figure 9), so that the cylinder looks as if it is floating above the surface – although the shadow counteracts this.

Figure 9
Figure 9.

If you turn it to zero though, you will get no reflection but the floor surface becomes very bright (Figure 10).

Figure 10
Figure 10.

In other cases you may get surface artefacts. I suggest leaving this alone unless you need to alter it to change the position of the reflection for some reason.

Rule 8. Leave the Reflect node RayBias setting alone in most cases.


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