Hi,
I'm considering camera mounts and active markers somehow.
But I'm wondering
1.
Can the camera mount ($49) be rotated by only 1 axis? I'm not sure, but I'm just conjecturing from the picture. Surely, we can rotate the camera while bolting, then it means we can rotate by 2 axes. Then, we should be cautious when we attach the mount on the wall to make the camera see in the disired direction?
2.
Using V100, ordinary markers can be seen when they are placed within 6m apart from a camera. Can the active marker be seen from farther distance? Do you know the limit exactly? I want about 10m as a maximum.
And how can I supply voltages to active markers? I don't know from the picture because I'm not familiar with circuits. Do I need to make circuits or can I get a small voltage source product (like commercial batteries) for each marker?
3.
Sync cables are 15ft long. Are there any products to extend the sync cable?
Thanks,
mount and active marker
Re: mount and active marker
1. don't know. have not used that particular mount before. I usually recommend the pipe clamp with the 3 way head from bogen. Its very flexible and I'd rather just mount some plumbing parts on the walls for the pipemounts to attach to than go for actual wall mounts. That way, the pipemount and head can move to other locations easily. Also, the 3 way head works on bogen tripod legs as well, so its an investment in wall mounts and in tripods. Dual value.
2. depends on the marker you construct. I've had some active markers I built years ago visible at about 10m away. I didn't find the max range as I ran out of room.
The last time I built an active marker set, I ran them in strings, kind of like x-mas lights. I ran a string of 6 off of a 9volt battery. I was doing my own soldering and mounting. They were different LEDs than the ones NP sells.
I've been keeping my eyes out for good easy LED mounts and power distribution systems. I've not found anything particularly appealing just yet. If you find anything, do please share.
I think if I were designing today, I'd be designing a system thats meant to string, but has variable length cable choices in between markers. Consolidating the power supply keeps the markers smaller and lighter. But the cables need to be the right length to stay out of the way but allow correct marker placement.
If you look online, you'll find plenty of information about wiring up LEDs. Nothing that goes beyond basic high school physics as far as prerequisite knowledge goes.
3. sync cables are standard RCA cables. So you can use radioshack parts with them with no problem. The 15 foot length is not a maximum length for the signal. I personally recommend 2x15 foot RCA cables for every 1 USB cable and 2 RCA female to female barrels per USB cable. That way, your RCA runs can be the same as your USB runs and you can do all the barreling at the hubs along with the USB. I zip tie my RCAs to my USBs to simplify the cabling process.
2. depends on the marker you construct. I've had some active markers I built years ago visible at about 10m away. I didn't find the max range as I ran out of room.
The last time I built an active marker set, I ran them in strings, kind of like x-mas lights. I ran a string of 6 off of a 9volt battery. I was doing my own soldering and mounting. They were different LEDs than the ones NP sells.
I've been keeping my eyes out for good easy LED mounts and power distribution systems. I've not found anything particularly appealing just yet. If you find anything, do please share.
I think if I were designing today, I'd be designing a system thats meant to string, but has variable length cable choices in between markers. Consolidating the power supply keeps the markers smaller and lighter. But the cables need to be the right length to stay out of the way but allow correct marker placement.
If you look online, you'll find plenty of information about wiring up LEDs. Nothing that goes beyond basic high school physics as far as prerequisite knowledge goes.
3. sync cables are standard RCA cables. So you can use radioshack parts with them with no problem. The 15 foot length is not a maximum length for the signal. I personally recommend 2x15 foot RCA cables for every 1 USB cable and 2 RCA female to female barrels per USB cable. That way, your RCA runs can be the same as your USB runs and you can do all the barreling at the hubs along with the USB. I zip tie my RCAs to my USBs to simplify the cabling process.
Re: mount and active marker
Thank you for quick responses.
Now I have more questions.
1.
Can we increase the visible limit of markers farther than 6m by using more infrared illumination?
2.
I read the information on webpages, but I'm not sure. In case of using "Lens M12 3.6mm No-Filter $15" to increase FOV instead of the default "Lens M12 4.5mm No-Filter, Low Distortion $50", and using only LEDs instead of markers, then is the situation recommendable? I'm wondering because there are some reasons for cheap materials. I'm especially suspicious about "distortion".
3.
When using greater FOV lens, are there somethings that I should adjust or set in calibration?
4.
If the whole volume is quite big, calibration wand cannot be seen from cameras. Then, is it okay to use LED for the calibration?
Thanks,
Now I have more questions.
1.
Can we increase the visible limit of markers farther than 6m by using more infrared illumination?
2.
I read the information on webpages, but I'm not sure. In case of using "Lens M12 3.6mm No-Filter $15" to increase FOV instead of the default "Lens M12 4.5mm No-Filter, Low Distortion $50", and using only LEDs instead of markers, then is the situation recommendable? I'm wondering because there are some reasons for cheap materials. I'm especially suspicious about "distortion".
3.
When using greater FOV lens, are there somethings that I should adjust or set in calibration?
4.
If the whole volume is quite big, calibration wand cannot be seen from cameras. Then, is it okay to use LED for the calibration?
Thanks,
Re: mount and active marker
1
I've experimented with augmenting the illumination of the cameras without much success. Its an area I'm still experimenting with and I don't have any concrete advice at this point. The problem I've run into is that retroreflection requires that the light source be very close to the lense and the existing LED ring has the best proximity. Anything I've set up has really been too far away. Its possible this is also affected by the very small aperture of the cameras. I'm not sure.
2
in my experience, the Arena calibration does a good job of estimating the distortion of the 60 degree lense and reversing it out. I know Jim is always a little hesitant about it as well. However I've found in the past that in small spaces, the benefit of having a wider lense outweighs the potential accuracy loss of the lense distortion being slightly off model.
I'm not totally clear as to what you are asking beyond this, however. If you could explain a little more I can give it another shot.
3
In my experience, no. Nothing in particular. Its measuring the distortion on the low distortion lenses as well.
4
It should be. If you remove the visible light filters from the cameras, you can use a red laser pointer too, which is kinda fun. The cameras see that little dot REALLY well. There are also infrared laser pointers available. But they're a little pricey.
I've experimented with augmenting the illumination of the cameras without much success. Its an area I'm still experimenting with and I don't have any concrete advice at this point. The problem I've run into is that retroreflection requires that the light source be very close to the lense and the existing LED ring has the best proximity. Anything I've set up has really been too far away. Its possible this is also affected by the very small aperture of the cameras. I'm not sure.
2
in my experience, the Arena calibration does a good job of estimating the distortion of the 60 degree lense and reversing it out. I know Jim is always a little hesitant about it as well. However I've found in the past that in small spaces, the benefit of having a wider lense outweighs the potential accuracy loss of the lense distortion being slightly off model.
I'm not totally clear as to what you are asking beyond this, however. If you could explain a little more I can give it another shot.
3
In my experience, no. Nothing in particular. Its measuring the distortion on the low distortion lenses as well.
4
It should be. If you remove the visible light filters from the cameras, you can use a red laser pointer too, which is kinda fun. The cameras see that little dot REALLY well. There are also infrared laser pointers available. But they're a little pricey.
Re: mount and active marker
Hi,
I've considered many situations so far. Now I have one more question.
IR LED has a "viewing angle" (possibly the angle at which the power drops to half). And your active marker has 100 degs of viewing angle. I think there are many cases that more than 100 degs are required to be tracked by cameras. How do you think we can deal with this situation? (If fortunately the power at more than 100 degs is strong enough to be tracked, then it would be nice, but I don't think it will happen.)
Thanks,
I've considered many situations so far. Now I have one more question.
IR LED has a "viewing angle" (possibly the angle at which the power drops to half). And your active marker has 100 degs of viewing angle. I think there are many cases that more than 100 degs are required to be tracked by cameras. How do you think we can deal with this situation? (If fortunately the power at more than 100 degs is strong enough to be tracked, then it would be nice, but I don't think it will happen.)
Thanks,
Re: mount and active marker
more cameras. They give you more angular coverage.
or
more markers per rigid body to get more angular visibility.
you wont see a typical reflective marker past about 180 degrees in most scenarios due to occlusion. the thing you're mounting the marker on usually blocks it on the back side. So dropping down to 100 degrees at worst would require twice as many cameras or twice as many markers. However, the strengths of LEDs probably leave you somewhere in the middle. Its not that bad.
or
more markers per rigid body to get more angular visibility.
you wont see a typical reflective marker past about 180 degrees in most scenarios due to occlusion. the thing you're mounting the marker on usually blocks it on the back side. So dropping down to 100 degrees at worst would require twice as many cameras or twice as many markers. However, the strengths of LEDs probably leave you somewhere in the middle. Its not that bad.