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The world is a complicated place, Hobbes.[1] The lower "HazCams" hazard avoidance cameras (which captured those initial photos) are there to detect hazards (ro
by handedness 6y ago
The world is a complicated place, Hobbes.[1]
The lower "HazCams" hazard avoidance cameras (which captured those initial photos) are there to detect hazards (rocks, trenches, etc.). They are stereoscopic, lightweight, and high resolution.
My guess is that using color sensors would have either increased the 3D mapping precision or added weight/power/bandwidth requirements, or otherwise been less robust in that environment.
Those cameras were also pre-deployed for the landing phase and likely transmit more quickly due to the lower data information. The other cameras were shielded for the landing phase.
The navigation and other cameras are in color, and I expect we'll be seeing better images shortly.
[1] This comes to mind whenever a question like that is asked: http://4.bp.blogspot.com/-CWM1zDcmWXs/TroD0VsX4WI/AAAAAAAAAVA/Jc5bN5xSTkc/s1600/ch930919.gif http://4.bp.blogspot.com/-CWM1zDcmWXs/TroD0VsX4WI/AAAAAAAAAV...
- jxcl 6y ago> My guess is that using color sensors would have either increased the 3D mapping precision or added weight/power/bandwidth requirements, or otherwise been less robust in that environment. I think you meant to say decreased? In which case I think you would be correct! Camera pixels are made up of these things called photosites which don't by themselves record color, only brightness. In order to record color information, the photosites are placed behind a Bayer filter[1], which effectively reduces the resolution of the camera by 3, because in order to get the color of a pixel you need its red, green and blue component. Bayer filters also frequently have a small blurring filter in front of them to make sure that nearby photosites with different color filters get the information they need. If you're looking for the highest resolution image possible, black and white is the way to go! [1]: https://en.wikipedia.org/wiki/Bayer_filter https://en.wikipedia.org/wiki/Bayer_filter
- m4rtink 6y agoThat's why "real" space cameras usually have color filters on a carousel before the sensor - they take 3 pictures each with different filter and BAM, color! That way you get high regulation as well as color. You can also have some special (infrared, ultraviolet, etc.) Filters on the carousel, not just RGB.
- dylan604 6y ago>and BAM, color! and BAM, false color! FTFY
- handedness 6y ago> I think you meant to say decreased? I did, thank you. I think my brain had already skipped ahead to the added weight/complexity concept while my fingers were stuck on that part of the sentence. I should probably read things after I type them...
- whuffman 6y agoFYI - the HazCams on Perseverance are in fact in color (this is new, they were black and white on Curiosity)! Stereo precision was a concern based on the switch to color sensors, so there was some algorithmic work done to make sure it wouldn't cause an issue. (Source: https://link.springer.com/article/10.1007/s11214-020-00765-9 https://link.springer.com/article/10.1007/s11214-020-00765-9 - "The Mars 2020 Navcams and Hazcams offer three primary improvements over MER and MSL. The first improvement is an upgrade to a detector with 3-channel, red/green/blue (RGB) color capability that will enable better contextual imaging capabilities than the previous engineering cameras, which only had a black/white capability.")
- handedness 6y agoInteresting, I didn't know that. I knew the Cachecam was color, but somehow missed that detail, despite actually seeing the camera in person at one point...
- m4rtink 6y agoWow, real upgrades all around compared to Curiosity! What are they going to do next ? Put on board a solar powered Mars helicopter ?? ;-)
- handedness 6y agoAnd by "increased" I meant the "decreased" kind...