[Elphel-support] Eyesis 4pi

[Jan Kohout]

Dear Andrey, 
thank you very much for your answers. 
Have you sold any system in Europe yet? Or is there a sales representative 
in Europe, where we could have a look at the system?
Thanks, 
Jan


---------- Původní zpráva ----------
Od: support-list <support-list at support.elphel.com>
Datum: 17. 6. 2013
Předmět: Re: [Elphel-support] Eyesis 4pi

"Dear Jan,
please see the answers below.

> 1. How much does the quality of the image change with the speed of capture
- meaning how different is image captured at 2.5 fps from one captured at 5 
fps?

5fps is the maximal rate possible by the hardware when it is not limited by 
the recording speed that with the current camera is limited to 16MB/sec. 
Good quality images (good for the purpose of aberration correction, not just
viewing of the JPEG images) is about 2MB/5MPix frame. Each SSD records 3 
channels (15MPix combined) - that gives 2.5 fps. Higher frame rate will be 
possible with the cameras electronic based on the new system boards that we 
are now working on.

> 2. Since we already own a mobile mapping system and are not happy with the
camera, are you able to deliver just the imaging part of your system? Only 
the set of cameras capturing the sphere.

What we actually sell is the image capturing system, all the software we use
is Free software available for download under GNU GPLv3.0 license. The SSD 
when installed in the camera are part of the system, you can also transfer 
images over the network and record them on a host PC, but that would reduce 
the maximal recording rate from 16MB/s to 10MB/s (and so the maximal frame 
rate with the same good quality of images)

> 3. On your web you say it takes 30 minutes to create a panorama. Is this 
value correct, and does it apply for every panorama, or just for the first 
and the subsequent panos take much shorter? When capturing tens of thousands
images per day, the 30 minutes seem just impossible.

Most of the image processing time is lens aberration correction. You know 
that every lens has some aberrations, especially far from the center. It is 
not a big problem for most cameras, but is really important when you tile 
multiple images. And even as we use the best lenses we could find they still
have lower performance (especially in the corners of the individual tiles) 
than the sensor resolution, so we use the processing to do the aberration 
correction. Of course you may bypass that step and use any other software to
combine the acquired images, we are focusing on the camera hardware 
development. Our lens distortion calibration provide precise mapping of the 
acquired pixels to the corresponding rays in space and you may use to create
panoramas with other software at a much higher rate.

> 4. The SSDs you use - is there a chance to install bigger disks and 
increase operational time?

The SSD we use are installed inside the camera, they are 1.8" SATA and we 
can install different capacity. It is also possible to use mSATA format SSD 
with adapters, in the future we'll use just the mSATA devices.

> 5. Have you tested the positional accuracy of your system in the 
challenging conditions of urban canyons/tunnels? If so, what were the 
results? We plan to get as many daily kms as possible (up to 400) and then 
use the data for survey purposes - this requires very good stitching of 
panoramas as well as precise position and attitude. From the MEMS IMU you 
use, I don't have much confidence in the final accuracy, but I might be 
wrong.

Currently we do not have any software to process the IMU data and test 
positional accuracy. The hardware records high-resolution IMU data at the 
rate 2.5 Ksamples per second and records them combined with the image 
acquisition timestamps, GPS measurements and optionally pulses from odometer
to the same log with microsecond-resolution timestamps. We also do the same 
when calibrating cameras - during that process the rotational accuracy is a 
fraction of the angular minute and positional accuracy is better than a 
millimeter - this data can be used fro the IMU calibration. But as I wrote 
above - currently we only have the hardware recording that data, not the 
software to process it.

Andrey"
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