Modo plugin - Lights
- marton (Unlicensed)
Maxwell Render doesn’t have virtual light system as you have in modo, so the plugin has to convert modo lights to Maxwell emitter objects.
Directional Light
The conversion method of the Directional Light items depends on whether you checked the Physical Sun check box or not. In case you use the Directional Light object as a modo sun, plugin uses the location, time information of the modo sun to convert it to sun information for Maxwell environments. In this case the light geometry is not exported.
If it is a simple Directional Light item without sun parameters, plugin converts it as a distant emitter object (small circular geometry) with high emission power values.
For Directional light export the plugin uses a special parameter: Light Source Offset. (You can change the value of this parameter in the Maxwell Properties viewport.) Light Source Offset controls how far the light source is in reality from the virtual light model. If you want to have sun like light source, the light object should be really far from your scene center. The default (and recommended) distance is 150 km. From this distance the light rays are almost parallels, and this is how sun light should behave. An emitter object needs very high emission power value to light the scene from this distance, but if you set the distance shorter, lower energy level is still enough. (The exporter automatically adjusts the emission power according to the Light Source Offset value.) Normally the possible biggest distance is what you need, but in case you have other scene lights with much lower emission power values, the high setting of the Directional Light emitter can make it difficult for the render engine to adequately render the weaker emitters. In these cases you have to balance with the Light Source Offset value to keep the right sun light effect, but with the lowest emission power. In the following pictures you can see how this parameter changes the effect of the light. The first picture (from left) shows the original modo render. The second picture shows how well the plugin emulates modo Directional Light if the offset value is big enough - the cost of it is the enormous emission power value. On the third picture the offset value is smaller which means lower emission power, but the conversion is still OK. The fourth picture is an example for what happens if the distance is too low. The light effect feels very local (rays are not parallel).
Plugin can simulate the Spread Angle value of the modo Directional Light items. On the following pictures you can see some samples.
Spot Light
Plugin exports Spot Light items as a combination of an emitter sphere object and a cone geometry with reflective material. It is a very simple lamp model, but it simulates modo Spot Light items very well.
The exporter takes care of the Cone Angle and Soft Edge parameters of the Spot Light Item.
There is a special Spot Light parameter: Segments. This parameter sets the number of the polygon sides of the lamp geometry. If Segments value is too low, the side of the light circle will be squarish.
It is better to keep this value low, otherwise it will cost in render time.
Other light types
Photometric Light
Photometric Light export is very straightforward. Maxwell Render V2 can use IES and Eulumdat files, so the plugin simply passes the IES or Eulumdat file to the emitter material file. The exporter creates a small sphere object and assigns the previously created emitter material to it.
Point Light
Point Lights are exported as small sphere geometries with emitter material.
Dome Light
Dome Lights are exported as huge sphere geometries with emitter material.
Cylinder Light
Cylinder Lights are exported as cylindrical geometries with emitter material.
Area Light
Area Lights are exported as rectangular or elliptical geometries (it depends on the Area Light Shape control) with emitter material.
You can overwrite the automatically converted Light Material with an “*.mxm” file the same way as you can overwrite item materials (see sub-chapter Maxwell MXM item).
Light Properties
Radiance multiplier
Radiance intensity multiplier for the exported Maxwell light. The exporter tries to export the lamp emission material with the right radiance value, but you can further tweak it with this parameter.
Light Source Offset
(For Directional Light items) this parameter controls how far the light source is in reality from the virtual light model. If you want to simulate the effect of a virtual sun object, the light should be really far from your scene center. The default (and recommended) distance is 150 km.
In case physical Sun parameter is turned on, this parameter has no effect, because light will be exported as Maxwell Sun Light.
Segments
(For Spot Light items) set the polygon number of the virtual light object. More polygons = better quality, but it can dramatically increase the render time!
It is good to keep the segment number of the spot light object low because it can greatly affect the render speed. Be careful! If you set it too low, it will have negative effect on the rendered image quality.