Rendering
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Starting and Stopping a Rendering
Click the Render AutoCAD Viewport button on the palette to initiate a rendering of the current AutoCAD viewport:
By default, the rendering process will continue refining the image, pass by pass, until you tell it to stop by pressing the Stop Rendering button. This allows you to manage the trade-off between time and quality. The longer you allow the rendering to continue, the more closely it will resemble its fully-converged or "correct" result. You can stop a rendering after seconds, minutes, hours or days. It's entirely up to you.
Pressing the Pause Rendering button once will suspend the rendering after the current pass is completed. Pressing the same button again will cause the rendering to terminate as soon as possible. A suspended rendering can pick up where it left off by using the Continue button. Pressing the Close button on the window frame immediately terminates the rendering and closes the display.
You can continue to work in AutoCAD while a rendering is active, by pressing the Minimize button on the nXtRender display. The display can be restored at any time by pressing the Show Current Rendering button, or by using the Windows Taskbar.
Additional Notes
- nXtRender produces images by using real world luminance values. The process of converting luminance values to displayable pixels is called Tone Mapping .
- Here are some suggested number of passes for a satisfactory result under a few different scenarios (your actual results may vary):
- Default exterior scenes, 10-15 passes
- Exteriors with indirect lighting, 25-50 passes
- Interior artificial light simulations, 25 passes per set of 8 lights
- Interior daylight simulations, 50-100 passes
- Studio models, 10-15 passes
- If you do not want your rendering to continue indefinitely, you can use the Passes setting on the Render Settings tab to set an automatic stopping point. A Passes setting of 0, the default, means continue indefinitely until manual terrmination.
- An Autosave option is provided in the Render Settings tab to force nXtRender to save your rendering periodically. This may result in usable work even after a power outage has interrupted the process. See Saving your Rendering, below.
- The status bar at the bottom of the nXtRender display shows mouse-over information about each pixel in the rendering, including the RGB value (luminance) and the resulting color after tone-mapping.
Rendering Resolution
Set the rendering resolution in the Render Settings tab of the nXtRender palette. The Total Pixels option is an easy way to match the AutoCAD viewport exactly. The default setting of 300,000 pixels provides a good setting for doing proofs or images destined for the web. 3,000,000 pixels or more may be required for a final, printed, image.
Processing time and memory usage are directly (linearly) related to the total number of pixels in your rendering. The higher the resolution, the longer the rendering will take and the more memory it will require.
Saving Your Rendering
The Save Rendering button allows you to save your rendering to several different image formats. You can save to most formats while a rendering is in progress.
The Alpha channel versions of the file formats are meant to be used for high-quality compositing. Backgrounds will appear black when the rendering is saved with Alpha channel.
The .hdr and .exr formats store luminance data directly in a High Dynamic Range format. Non-luminance backgrounds, such as normal photographs, will appear black when saved in one of these formats.
The .nXtImage format is the native image format of the nXtRender rendering. It is the recommended format for storing your renderings, since it preserves the most information about your rendering. Images stored in this format can be manipulated in the nXt Image Editor and special FX can be added. From this editor, you can save to many popular standard formats, including all of the formats supported in nXtRender. You can also save to Piranesi (.epx) file format.
