I regularly upload photos to Google, and for the longest time, I could not figure out why some photos I would upload would be dated for the time I uploaded them, and some photos would be tagged with weird dates on them, and be displayed accordingly; that is, photos with the most recent date would be displayed first, while older ones would be further down the page.
This made no sense to me; why would photos I uploaded on a given day be displayed as if I had done so in the past? I accepted it as one of Google’s weird antics, then last night, I had an epiphany. I thought about the metadata associated with the photos I had uploaded, and wondered whether the information contained within it had something to do with it.
Every photo has a number of properties associated with it, and a lot of it is contained in the metadata in the photograph. You can read more about it here.
To make a long story short, I found out that a certain property caused Google Photos to classify certain photos differently, and the photos that were classed as the day I uploaded them did not have a creation date associated with them, whereas the ones that did have the date associated with them would be classed as the same date as the date of creation. For example, a creation date of February 16, 2012, would be classed under that date, whether or not you actually uploaded it at that date.
NOTE: To find out all the metadata properties associated with a given photo, see here.
The solution, then, is to strip the creation date information from the photos, so that Google Photos would class the photos on the same date you uploaded them. The trick is to use a command-line utility to accomplish the feat. The tool in question is called exiftool. This particular tool will strip all of the creation date information from your photos. You can read more about how to accomplish this here.
After I deleted all the other photos that had been classed as a different date, along with the photos that were classed as the date I uploaded them, I tried my theory out.
EXCALIBUR! IT WORKED!! All the photos were in the same grouping; no more looking for the photos that would mysteriously appear in other places. Every photo you process in this way will be classed as the day you upload them.
I hope this helps someone. Happy Hacking & Slacking!!