That's interesting about those ...\My Pictures\.Picasa3Temp... directories/files. As a long-time user of Picasa (and I recently upgraded to their last release "Sunset" version), I have played about with Picasa quite a lot, and I thought
I understood all its little quirks. However, I don't think I had ever come across the Temp folders you refer to. In fact, I can't even find them now - on backups or elsewhere.
Nor had I been aware that folders prefixed with a dot were invisible. Maybe because for years it has been my standard practice to show hidden and system folders/files in Windows Explorer settings, I had forgotten about the dot prefix being invisible. In fact for years I have used dot prefixes in my file naming conventions - a fact which moved me away from Locate32 search to Everything search - as the former can't handle dot prefixes and the author of the proggie said they shouldn't be used (!), or something.
And in my opinion, it's pretty cool that everything Picasa does is non-destructive, since it makes a backup of the originals. But if that's something you weren't aware of, it can definitely be alarming to discover GB of photos you didn't know existed.
- I have to agree wholeheartedly with the first sentence. Picasa is a superb image database management tool, and the developers seem to have put a great deal of thought into its design. I don't know of any FREE or Paid image database management tool which has an equivalent comprehensive and stable functionality - which is why I still depend on it.
The second sentence I don't really follow though, because a reading of the Picasa instructions for use will tell you about the non-destructive keeping
From experience of the digitisation of hardcopy cadastral into images, it is an important requirement to be able to get back to the original hardcopy
of any given image, and equally to the original unmodified image
of any subsequently modified
This is not only because altered images tend to look different depending on the peculiar characteristics of the display
type being used at the time - so might look not so good when you migrate to (say) another video/laptop display type - but also (and mainly) because a basic rule of thumb for image data protection is always keep the originals intact
because every change is theoretically potentially lossy
as it involves a copy/save of the image data (there's some interesting research that demonstrates how this works out in practice, when images are repeatedly copied
and which copies are copied again, etc.).