Rendering Thumbnail Images from Geometry
One of the strategies for generating Thumbnails involves rendering an image from the geometry or spatial information in indexed records. Although this is generally the slowest method of generating thumbnails, it does offer some fine control over the styling of resultant shapes with the Style Rendered Shapes controls. Rendering Thumbnails from Geometry can be very time-consuming - see this article for tips on speeding up the rendering process.
Enabling Thumbnail Rendering from Geometry
To enable rendering thumbnail images from geometry :
Go to Manage > Discovery > Locations
Click the Edit icon next to a location
Select the Thumbnails tab
On the Thumbnail tab for that location, select Render Images from Geometry from the Strategy pull-down menu
In the next dialog under Schedule, select from the dropdown to set when you want this task to be be triggered
Under Security, select from the dropdown the default or customized user groups on your instance that you want this task to be applied to
Click Save when you are done