How to improve default thumbnails from Revit or use a custom thumbnail
By default, AVAIL displays the thumbnail provided from Windows. If you look at the thumbnail for the same family in your Windows File Explorer, it will look the same.
Windows, in turn, gets the thumbnail provided by Revit, which generally uses the view you most recently saved.
One way to get a better Revit thumbnail is by creating and saving a preferred view in Revit.
If the preferred thumbnail isn't displaying, you may need to select the Thumbnail Preview by selecting Save As > Options > and then selecting preferred view under the Thumbnail Preview list.
There is also an option to create custom thumbnails for content in AVAIL. I'll link a video example below which shares one third-party option that specifically helps with Revit family thumbnails.
Some Revit thumbnails don't generate an image. Why?
Occasionally, you will see a Revit thumbnail that appears as the Revit logo and not a thumbnail of the family (image). You can check to make sure this is not an AVAIL issue by looking at the same file in Windows File Explorer thumbnail view. If you see the same Revit logo image, you know it's a Revit file issue.
We are not completely sure why this happens, but it appears to be a Revit file issue and not an issue with the manner in which AVAIL generates the thumbnail. Remember, AVAIL uses the underlying Windows OS to generate thumbnails (custom thumbnails are a different matter).
So, what's the fix?
You can open the Revit file and generate a new thumbnail using a different view. In some cases, updating the Revit version will help (if that works with your workflow)
For more information on creating custom thumbnails, see our article here