How the Sun shines for Google Maps?
I've read many articles and reviews about Google Maps. It's quite amazing how these guys have made such great product using almost only common browser based programming.
While playing with it and looking at the way it pinpoints places on the map, I realized a little detail that got my attention... the shadows.
When you see a shadow it necessarily doesn’t mean we will have six more weeks of winter, but there must be a light source projecting that shadow. Thus, taking in account the maps show geographical locations then the more obvious source for this light is the Sun.
I'm not and astronomer or a scientist, as I stated before, I’m just a wannabe photographer who knows a little bit about lighting sources and shadows. I pasted a screenshot in Photoshop and tried to figure out the more I could about the facts that caused the projection of the shadows. (No publicity was intended for the places shown in this map, I just made a generic search within my city and that’s what came out)
As a fact, the light source always come from the opposite side of the shadow, so I measured the angle of the light source with respect to the cardinal points, and it gave me the shadow has a deviation of 43º from East to North (all calculations here are based on aproximated values), which means the Sun must be at 43º from West to South or, as is the same, 47º from South to West. I googled and found out this angle is called Azimuth.
Then, I tried to figure out what the elevation of the Sun was. I googled again and found a Shadow Length Calculator, which uses the height of an object and Sun’s elevation for the calculation.
Using photoshop, I determined the virtual height of the pin plus the balloon, and the length of their shadow (Note to Google: Your maps don’t show the scale ruler, so I had to copy it from Mappoint). From this, I could determine the elevation of the Sun was approximately 52º.
Furthermore, I wanted to calculate the date and time when the Sun was in that specific position, but I couldn’t find anything out there in the internet that let me calculate exactly those values, because they depend on the latitude, longitude and other parameters I barely understood. All I was able to determine was the time was in some moment in the afternoon and the date was when the Sun followed its winter path.
Finally, after my rudimentary analysis of Google Maps’ shadows in any given location, I found they are not being projected based on the Sun’s position for such specific place's latitude and longitude, neither for the current date/time in that place.... but that would have been a nice feature to be considered by Google.
click to see a bigger image
Note to readers: If you want to add anything to my analysis, or even correct something I did wrong, please feel free to write me to explicitexposure[at]gmail[dot]com and I'll post it with pleasure.
While playing with it and looking at the way it pinpoints places on the map, I realized a little detail that got my attention... the shadows.
When you see a shadow it necessarily doesn’t mean we will have six more weeks of winter, but there must be a light source projecting that shadow. Thus, taking in account the maps show geographical locations then the more obvious source for this light is the Sun.
I'm not and astronomer or a scientist, as I stated before, I’m just a wannabe photographer who knows a little bit about lighting sources and shadows. I pasted a screenshot in Photoshop and tried to figure out the more I could about the facts that caused the projection of the shadows. (No publicity was intended for the places shown in this map, I just made a generic search within my city and that’s what came out)
As a fact, the light source always come from the opposite side of the shadow, so I measured the angle of the light source with respect to the cardinal points, and it gave me the shadow has a deviation of 43º from East to North (all calculations here are based on aproximated values), which means the Sun must be at 43º from West to South or, as is the same, 47º from South to West. I googled and found out this angle is called Azimuth.
Then, I tried to figure out what the elevation of the Sun was. I googled again and found a Shadow Length Calculator, which uses the height of an object and Sun’s elevation for the calculation.
Using photoshop, I determined the virtual height of the pin plus the balloon, and the length of their shadow (Note to Google: Your maps don’t show the scale ruler, so I had to copy it from Mappoint). From this, I could determine the elevation of the Sun was approximately 52º.
Furthermore, I wanted to calculate the date and time when the Sun was in that specific position, but I couldn’t find anything out there in the internet that let me calculate exactly those values, because they depend on the latitude, longitude and other parameters I barely understood. All I was able to determine was the time was in some moment in the afternoon and the date was when the Sun followed its winter path.
Finally, after my rudimentary analysis of Google Maps’ shadows in any given location, I found they are not being projected based on the Sun’s position for such specific place's latitude and longitude, neither for the current date/time in that place.... but that would have been a nice feature to be considered by Google.
click to see a bigger image
Note to readers: If you want to add anything to my analysis, or even correct something I did wrong, please feel free to write me to explicitexposure[at]gmail[dot]com and I'll post it with pleasure.
posted by Mario at 2:00 PM
1 Comments:
Thank you for this most amusing post that, while not what I was looking for (any prior art on making a daylight overlay on a Google Maps API site, to be precise), was a good laugh anyway. :-)
You might have noticed that the light source that shines on Google's maps sits somewhere in your room, as it has this steady angle whichever part of the planet you go to.
...Or even the moon! (But let's not go there. It's a silly place. ;-)
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