There are some current limitations when using 3ds Max Photometric lights with MAXtoA. Here is a brief list of what is not supported:

•    Some light shapes do not support Spherical distribution.
•    Only supports ray traced shadows – other settings are ignored. 
•    Exclude / Include is not supported.
•    Incandescent lamp-color shift is not supported.
•    The light shape is not visible to the camera rays.
•    Shadow parameters are not used.
•    Legacy Atmosphere & Effects are not supported.

Note that the Physical Scale value in the Exposure Control (Environment and Effects) has an influence over how your 3ds Max and Arnold lights render. You may need to Disable or adjust the Physical Scale to get the intensity you expect.

There is a generic Arnold Light object where you can select the type of light in a combo and the parameters will change dynamically according to the selected type. This can be found under the lights menu in the create tab.

Choose Arnold from the light list

 

3ds Max scenes (particularly architectural scenes) setup for other rendering engines will not necessarily convert well to MAXtoA. Arnold does not currently support physical units for lights, and a conversion process is not straightforward. You may need to adjust Intensity and Exposure parameters for your lights to match.

Common Light parameters

As well as honoring the standard 3ds Max light parameters, the Modify Panel will also show the following Arnold parameters:

Intensity

Exposure (f-stop)

Normalize Energy

Samples

More information about light samples and removing noise can be found here.

Volume Samples

Volume Samples does not apply to the Atmosphere Volume shader. To improve the quality of the Atmosphere Volume shader, you must increase the Atmosphere Volume samples.

Shape

Type

The shape of the light. Choose from Point, Distant, Spot, Quad, Disc, Cylinder Light, Skydome, Photometric and Mesh.

Types of lights available in MaxtoA

Light Shape Visible

When enabled, the shape of the light is visible in the render as a self-illuminated object.

 

Shadow

Cast Shadows

Atmospheric Shadows

Shadow Color

Shadow Density

Contribution

 

 

Per-light scaling for Camera, Transmission, Diffuse, SpecularSSSIndirect and Volume. Weights scaling the light contribution to each of those components independently. Should be left at 1 to produce physically accurate results.

Indirect

Max bounces

AOV Light Group

Light Path Exressions do not currently work in MAXtoA. They are planned for a future release.