About the Differences Between Rendering In the Current and An Earlier Release

Each render engine calculates lighting and materials differently, and as a result the rendered images produced will be different.

Note: Starting with AutoCAD 2016-based products, a new render engine was introduced as a replacement for the "legacy" renderer available in AutoCAD 2015-based products and earlier. This change affects the way 3D models created in AutoCAD 2015-based products and earlier are rendered to an image. You might need to make changes to the lighting, materials, and render settings of your 3D models to generate rendered images of the desired quality and appearance.

The following table provides a comparison of the features supported by the renderer in AutoCAD 2015-based products and earlier releases against those in the current release.

Feature	Legacy Renderer	Current Renderer	Comments
User-defined Lights	X	X	Legacy Renderer Generic and photometric lighting were supported. Attenuation could be configured on a per light basis with generic lighting; LIGHTINGUNITS = 0. Current Renderer Only photometric or physical based lighting is supported. All lights are calculated using inverse square attenuation, and changes to the attenuation related properties of all user-defined lights is ignored. Note: The LIGHTINGUNITS system variable must be set to 1 or 2 to properly calculate lighting and shadows. If LIGHTINGUNITS was set to 0 in an earlier version of AutoCAD, lights are still calculated using inverse square attenuation even if a different option was specified for a light. Scenes rendered with LIGHTINGUNITS set to 0 can result in darker images. Adjust the intensity of the lights in the scene or use image-based lighting to increase the brightness of the final rendered image. Note: The current value of the FACETRES system variable can affect the quality of the shadows that are generated by the lights in a scene.
Casting and Receiving Shadows	X	/	Legacy Renderer The generation of shadows could be controlled on a per light basis. The casting and receiving of shadows could also be controlled on a per object basis. Current Renderer All lights generate shadows. The properties of individual user-defined lights related to shadows is ignored, and all objects cast and receive shadows in the scene. Note: Shadow related properties of a user-defined light are ignored, along with the current value of the Shadow Display property of all graphical objects in a drawing.
Backgrounds	X	X	Solid color, gradient fill, image-based, and Sun & Sky backgrounds are supported. In addition to the custom 2D backgrounds supported by both renderers, the current renderer also supports the use of image-based lighting (IBL) maps. IBL maps can be combined with a custom 2D background. Note: Viewpoint must be set to perspective and not parallel to use the Sun & Sky background type.
Sun & Sky Based Lighting	X	X	Sun & Sky based lighting is supported. Legacy Renderer Supports all three states: Off Sky Background Sky Background and Illumination Current Renderer Supports only two states: Off Sky Background and Illumination
Render Presets	X	X	Render presets are supported by both renderers and maintained separately for backwards compatibility. Render presets for the legacy renderer are not compatible with the current render, and those created for the current renderer are not compatible with the legacy renderer.
Materials	X	X	Materials can be created and attached to objects before rendering. Note: Materials originally created for use with the legacy renderer might need to be updated when used with the current renderer. For example, a pure white material can result in a rendered image being too bright.
Image-based Lighting (IBL)	--	X	The current renderer supports the use of image-based lighting. Image-based lighting affects the light calculated for a scene and can optionally be applied to the background of a rendered image.
Exposure/Tone Mapping	X	X	Legacy Renderer Supported logarithmic exposure. Adjustments could be made to the global brightness, contrast, and midtone values of the lighting in a viewport or rendered image. Note: Exposure was supported only when photometric lighting was enabled; LIGHTINGUNITS = 1 or 2. Current Renderer Supports photographic exposure. Adjustments can be made to the exposure and white balance of a rendered image.
Fog and Depth Cue	X	--	Fog and depth cueing cause objects to appear faded as they increase in distance from the camera.
Render to Window	X	X	Current view can be rendered in a separate window.
Render in Viewport	X	X	Current view can be rendered in the current viewport.
Render Region	X	X	Rectangular area can be specified and rendered in the current viewport.
Render Online	X	X	A 3D model can be uploaded to an online rendering service. Rendering calculations are performed by the service and a rendered image is returned. Note: The rendering service supports photometric lighting only, and uses a rendering engine similar to the one in the current release of the product.