Let's assume that for some reason something got corrupted and you want to regenerate the thumbnails for a given workbook in a PowerPivot Gallery. You can either change the properties for the workbook, which will create an event that will trigger the regeneration of the thumbnails (more details at Dave's blog here: http://bit.ly/9Z23pt). Under the hooks, adding a new document to a SharePoint library (PowerPivot Gallery included) or modifying a document in a SharePoint document library causes SharePoint to throw either a itemAdded or itemUpdated event. The event is observed and handled by PowerPivot, which calls the GetSnapshot.exe as the farm account passing along a few parameters.
If you'd like to try it manually, open a command prompt (or PowerShell prompt) as the farm account (or login as the farm account);
Find the folder [SystemDrive]:\inetpub\wwwroot\wss\VirtualDirectories\80\bin;
Run GetSnapshot.exe with the following parameters:
GetSnapshot.exe <server> \"<DocumentPath>\" \"<OutputFolder>\" <tempFileSeed> [<maxSnapshotCount>] [<timeoutSeconds>]
is the basis of the file name of the generated thumbnails;
is the maximum number of snapshots to be taken;
is the maximum amount of time in seconds before the process is aborted.
C:\inetpub\wwwroot\wss\VirtualDirectories\80\bin>GetSnapshot.exe "http://myserver" "http://myserver/PowerPivot Gallery/myWorkbook.xlsx" "C:\Users\marianotn\Desktop" marianotn_test 26 300
Disclaimer: This posting is provided "AS IS" with no warranties, and confers no rights. The GetSnapshot.exe is part of PowerPivot for SharePoint. It’s not redistributable, and not it was not designed to be used any other way than by the PowerPivot for SharePoint system.