What is the difference between Corona Bitmap and 3ds Max Bitmap node?

When using Corona Renderer, bitmaps can be loaded using two supported nodes in the material editor:

  1. Corona Bitmap
  2. 3ds Max native Bitmap node

Note: V-Ray HDRI loaded must never be used with Corona Renderer, as it always produces incorrect results, and may cause some additional issues, for example when using distributed rendering!

Both of them will produce almost identical results, however there are some advantages of using the Corona Bitmap over 3ds Max Bitmap node:

1. Corona Bitmap Features

1.1. Rendering speed

In most cases, using the Corona Bitmap node will result in faster rendering:

Complex materials using textures loaded with Corona Bitmap only. Render time - 1:30. 

The same scene rendered with all textures converted from Corona Bitmap to 3ds Max Bitmap. Render time - 1:35. The difference may not seem to be big in such quick rendering, but it will be definitely noticeable in the long run.

1.2. Various filtering modes and blurring

The Corona Bitmap node offers various filtering methods, which affect the appearance of the texture, and can be also used to further decrease render times:

Example 1 - low resolution bitmap used as a bump map:

Bilinear filtering. Render time - 00:21. 

This is the default method, which balances rendering speed and quality. If the texture is in low resolution, pixelated edges may be visible on closeups.

Bicubic filtering. Render time - 00:23.

This filtering method is slightly slower, however it provides better quality in case of low resolution textures. The edges are much more smooth than with bilinear filtering selected. 

Nearest filtering. Render time - 00:20.

This filtering method keeps edges sharp and thus produces pixelated output. It should not be used on textures which are seen close up. It is however renders fastest. 

Example 2 - HDRI environment:

Bilinear filtering. Render time - 00:53.

Bicubic filtering. Render time - 01:11.

Nearest filtering. Render time - 00:46.

Example 3 - Blurring:

Regardless of the filtering type selected, blurring can be also adjusted for the Corona Bitmap:

Bilinear filtering. Blur = 0,01.

Bilinear filtering. Blur = 1.

Bilinear filtering. Blur = 2.

2. How to convert all 3ds Max Bitmaps to Corona Bitmaps at once?

The Converter Script can be used for this. Simply run the converter (right click in any viewport, select "Corona Converter" menu item), and then press "Bitmap > Corona Bitmap". 

Corona Bitmaps can be also converted back to 3ds Max Bitmaps.