Google Earth Satellite Image Scales for Visitor 3

[OChristie 0]

Maybe as a sticky?

I would like to find some more information on the scales (height) that one should capture the image in google earth.

For example, if I am creating a 1024x1024 map, what would the recommended Satellite Height be in GE?

Is their a pattern to follow for each map size parameter?

Any examples would be greatley appreciated.

I suppose my real aim is to write a small program that does all the calculation for you and it just returns the Height Value Needed.

I hope this thread helps people out for future reference.

[Nicholas Bell 0]

Well what you want is the GE pixel dimension to match whatever you are using in V3.  My sat maps are all 1 px = 1 meter.  What height you use in GE is monitor resolution dependent.   By taking a screenshot of GE and using the distance scale (in the lower left corner), you can determine the number of pixels per meter real world dimensions at the height of your screenshot.

I then use Fraps to snap images of the entire image, which I cut and paste together. Make sure you turn off the side bar, nav tools etc to maximize your image, and have Terrain turned off to avoid distortion.  Very important to ensure you don't change the GE height above ground by mistake, and use the 'R' key to ensure alignment.  Once I have the entire area pieced together I can resize it using the ratio I determined when I took a screenshot with the scale visible.

Obviously you want to get the best image, but zooming in all the way in GE is not always the answer because their image's resolution.  Plus the more you zoom in the more images you have to take and piece together.  Of course if you zoom out too far you lose a lot of detail, too.  So you have to balance.

I have a registered copy of the program called Google Maps Image Downloader which worked great - note past tense.  It would download the pieces and stitch them together for you   However, it no longer works for me...my guess is that GE got wise and found a way to block it entirely (it would temporarily stop me if I got to "greedy" with the auto-downloads).  It's still available, so maybe it's just me it won't work for anymore.

[OChristie 0]

I have Google Earth Pro, it gives you the option to save a 4800x4800 pixel image. So for example per say, if i was to create a 4096x4096 Map with a 10.0m Cell Size. My Map would be 40960x40960 in size, and my terrain pixel if 1px/1m size would be 40960x40960?

So therefore, My height in Google Earth Pro would have to be 4.096km for the Satellite image?

[luki 53]

High parameter is only the view high of the camera not the distance

Use the "*Lineal Tool" to measure  the size then you can zoom to the required high.

for ex.

-Draw a vertical line* with 4096m length

-Zoom the window that the edge of the line fits the screen

-save the image

-resize to 4096

If you want 1px 1m sat map for your  40960 map you would need to capture 100 of this pics (depending on landmass). If you got a atomfueld supercomputer then do it

[OChristie 0]

Thanks Sgt.Ace

I will experiment.

So basically.

1024x1024 map 20.0 cell = 20480 Sat Image.

Bit unrealistic, but hey i can work with things

Cheers all.

[Nicholas Bell 0]

I think you are not understanding the most important part - you either need to resize your GE image, or take it from the correct altitude, so the scale is correct.

Using the ruler you can see that 111 meters real world = 230 pixels.  Therefore each pixel equals .48 meters.  If your doing a 1024x1024 map with 20 meter cells, your sat image would not be 20480x20480 at 1 px=1 meter. Rather, it would be 42,667 x 42,667 pixels.  Obviously this is too much, so you would want to create your image from a higher altitude to reduce the size of the sat image.  This example image was taken at a height of 383 meters above sea level.  By doing some math you can determine that if you take the image at 798 m asl then each pixel would equal 1 meter in your sat image.

Note that you can have you sat image at more than 1 px = 1 meter, but then ArmA stretches the image to fit and it will not look very good.

Hope this makes sense.  It's not as difficult as I might be making it seem.