Why does a moving airplane appear twice in an Apple Maps satellite image?
Asked 8/27/2024
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In an Apple Maps satellite image, I can see what looks like two airplanes at the same location. One is a bright aircraft with separated RGB colors, which I understand could happen if color channels were captured at slightly different times while the plane was moving. But there is also a second, darker and surprisingly sharp airplane shape. If the image is focused on the ground, why does an aircraft far above it also appear sharp? Is this a special artifact of satellite imagery processing?
Originally by David. Source · Licensed CC BY-SA 4.0
David
1y ago
2 Answers
2
The second airplane though is myterious to me. It is darker and surprinsingly sharp
This image has almost certainly been pansharpened. The process of pansharpening combines intensity taken from a high-resolution image having a single channel, with hue taken from a lower-resolution image having multiple channels, to produce an image with more information than either of its inputs alone.
Notice in particular that the sharp airplane image is colored in brown and green — the colors of the field, path, and trees below it. I don't know why it's so dark, but I'd guess that the particular algorithm used refrains from making an output pixel much brighter than the input color was, to avoid amplifying noise from dark pixels when edges don't perfectly align.
Originally by Kevin Reid. Source · Licensed CC BY-SA 4.0
Kevin Reid
1y ago
0
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The most likely explanation is not focus, but image processing. Satellite map imagery is often pansharpened: a high-resolution single-channel image is combined with lower-resolution color data to make a sharper color image.
In this case, the bright airplane with shifted colors is consistent with a moving object being recorded differently in the color channels. The darker, sharper “second plane” is likely an artifact from the pansharpening step. A high-resolution luminance/detail layer captured the aircraft sharply, while the color information came from the ground below. That’s why the darker plane can appear tinted with ground colors like brown and green.
So the second aircraft is probably not a separate exposure of another plane, nor evidence that the satellite was focused on both ground and plane. It’s more likely a processing artifact created when a fast-moving object is combined with color and detail data that were not perfectly aligned in time or resolution.
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AI1y ago
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