by Andrey Filippov
Designing for low parallax
texture_tiles
When we started working on Eyesis project our first goal was to make the panoramic head as compact as possible to reduce parallax between sensors. That not only reduces the stitching artifacts but also decreases the minimal distance to object without dead zones between the individual camera.
The first practical step was to reduce the PCB area around the sensors, especially in one direction, so multiple camera boards can be placed closer to each other, For that purpose we preserved the basic design of the proven 10338 sensor board, just changed the layout to make it more compact. The board 10338D is just 15mm wide – more than twice less than the older design.
Next step was to run mechanical CAD program and try to place the boards and lenses. Most of the Elphel cameras were designed for the C/CS-mount lenses, but when I tried to place them I immediately found out that when using 10 or 8 cameras around even the C-mount thread (CS is the same size but even closer) will be the limiting factor, not the sensor PCB that we already made smaller.
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by Olga Filippova
Eyesis camera shade, before anodising
3 x 10353 processing boards with 3 connected sensors each
The first 3 Elphel-Eyesis prototypes are nearing completion. Even though there were delays from our suppliers we finally received the last remaining parts and can now finish the camera and data storage assembly.
There were concerns that the pole and its attachments could have aerodynamic problems and that the system could be a whistle at higher speeds.
Today we tested the assembled camera shade for acoustical noise while moving at speed 30-55 mph, luckily the tests proved that there was nothing to worry about.
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by admin
Andrey spent months of planning and designing these parts and yesterday we finally had the joy of assembling the first panoramic camera head prototype utilising 9 sensor boards. This new panoramic camera head is called Elphel Eyesis. A few metal parts are still missing but the heart of the system – the optical part – is now completed. The extremely small size drastically reduces parallax (wikipedia explanation) see ruler for size comparison. The system allows to gather 360° panoramas at ~38 Mpix (45Mpix before stitching) at min. 5 fps (lower resolutions allow higher fps while covering the same field of view). The images below also show the pretty complex internal mechanical systems that allow each sensor to be mechanically fine tuned (2 axis tilt, focus plane distance).
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by Andrey Filippov
Not much progress with the 10373 board in the last 3 weeks – just cleaned up debug wiring and prepared the board for the visit from SlimLogic Ltd. The software for the 373 camera is going to be based on OpenEmbedded and I would like to set up everything correctly before getting deep in the modifying the existent codebase.
Meanwhile we tested the redesigned sensor board (will work with the 373 camera too) to make it smaller. All the current sensor boards (but the ones with a large Kodak CCD) were the same size – 31.4mm x 31.4mm – it did not change since the times of old Zoran 1.3MPix sensor. Since then the sensors became smaller and less components were needed for the power conditioning too.
The sensor board size is especially important for the panoramic video were it is desirable to keep lenses as close together as possible to reduce the effect of the parallax. For the still imagery panoramic photos it is possible to rotate a camera precisely around the entrance pupil of the camera lens, but for the video (or even some imagery) it is not a solution.
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