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The so-called "Ghost BSDF" can also be created in a normal material. It's a normal BSDF with Transmittance set fully white (255,255,255) and Nd = 1. It renders as air and the rays don't refract when travelling through it, so it's very fast. Click on the thumbnail to see an example:
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Light types
The different types will show different gizmos in the viewport:
Area Type
- The Area type will generate an emitting square of 50x50cm with a target by default. This will only emit light from one side in the direction of the target. The emitting geometry can be converted to a sphere, in which case the target is disabled. Depending on the type of Emission, the options change. It can be by Color, by Temperature or using an image.
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- Color emission allows to choose a particular uniform color of emission and the intensity in specific units. When you choose Power and Efficacy, Lumens or Candelas the intensity will be distributed uniformly over the surface of the emitting object (watch out, as a 100W emitter will barely produce any light if assigned to a 10x10m plane, but will look very bright if applied to a 1x1cm plane. The intensity when you use Luxes (lm/m2) and Luminance (cd/m2) on the other hand, will vary depending on the size of the object. The look of a 10x10m plane will be very similar to a 1x1cm one, but smaller one will actually emit less light than the bigger one.
- Temperature emission specifies both the intensity and color based on the color temperature value.
- HDR Image emission allows to choose an image to emit light (a TV screen could be achieved with this). Although it is strongly advised to use HDR or MXI files, you can also use other low dynamic range images as jpg, png and so. As units cannot be specified for this, you can change its intensity with a multiplier.
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IES Type
- The IES type generates an invisible ball which is the origin of emission and allows to assign an .ies or .ldt file to it. These files are usually provided by the lamps or spots manufacturers and represent the light distribution generated by the whole lamp. IES type is particularly useful to represent exactly the look of a particular lamp in the market without having to model the whole lamp. Maxwell includes a small collection of these type of files in its installation folder for you to test. In its panel you will find a multiplier for the intensity and an option to show the lobe (a point cloud representation of the "shape" of the light distribution) in the viewport. It also allows to set the color of the light.
IES type options
Spot Type
- The Spot type simulates a standard spotlight. It generates a cone with an emitting polygon inside (a small triangle); this geometry is always hidden to camera at render time, although it's visible in reflections and refractions unless you activate the option to hide it. It allows to set the cone angle (the highlight area) and the fall-off angle (measured from the cone angle), as well as the type of fall-off (linear, quadratic,...).
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- Projected texture box allows to load an image. In this case the gizmo of the MxLight will change into a pyramid resembling the proportions of the loaded image and the light will work as a cinema projector. You can project any image format, both low dynamic range images (like jpg, tga or png), high dynamic range images (like hdr, exr or tiff32) or even procedural textures. In this case, the falloff angle grows to the inside of the main cone creating a vignetting effect and darkening the corners of the image.
You can find more information about how Spots work in Maxwell in this page: Spot emitters
Select and Manipulate Mode
All the types allow for some extra controls when you activate "Select and Manipulate" button in 3dsmax.
Depending on the gizmo you can resize, rotate, change the spot angles or modify the intensity of the light. For example, in the Area type, you can resize the plane by dragging from its borders; in the case of the Spot type, you can change the cone or fall-off angles by dragging from the base of the cones.
Different options in Select and Manipulate mode
The intensity handle allows to modify the intensity of the light just by dragging the small box along the light's axis. The small blue dot represents 0 intensity; by default the manipulator will show 1m away from the blue dot; this represents 10000 lumens. The light changes quadratically to make it easier to select either low or high intensities.
This graphic shows how the light intensity grows quadratically with the distance
Additionally, the color of the intensity handle changes with the color of the light in order to give an idea of how the light will look like.