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camera_placement_notes.md

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Notes on the camera placement

Please consider these guidelines when setting up a test environment for your Telraam.

Suitable location selection

  1. The camera should preferably look perpendicular to the traffic flow, except in special cases where a slight offset is OK.

  2. The camera should be placed as high as possible (top of the window preferred over bottom, first floor preferred over ground floor - latter is strongly advised against)

    • Should the camera be still on the ground floor, locations where parking spaces are present on the near side of the road should be excluded, since here there will be times often that a parked car blocks most of the street’s traffic.
  3. The frame of view should be set – with the camera pointing slightly downwards – such that the bottom of the field is aligned as low as possible (set by the outer edge of the window sill) or with the closest edge of the pedestrian walkway, and the top of the field of view contains some space over the furthest pedestrian walkway or car lane. In general, a camera pointed such that the centre of the field is pointed to the centre of the road surface used by cars is good. If the camera is set higher than the ground floor then this will probably never be an issue, but avoid having the horizon/sky in the frame. Should any sky be visible on the camera after a good pointing is achieved following the previous guidelines, then point the camera further down until the sky is not in the frame anymore. It is better to have more of the window sill than having the sky.

  4. The camera should contain only one street. If the location is close to crossroads, point the camera slightly away from the crossroads, so only one street is visible. Cameras looking over crossroads are to be avoided.

  5. The camera needs a free, unobscured view of the road, meaning that there should be no stationary objects (lamp posts, trees, security railing, balcony structure, window frames, etc.) between the camera and the road surface(s), especially in the early stages. Trees on the far side, or at the edges of the frame are acceptable.

    • An insect net could be disturbing. We expect that the netting itself would not be an issue, but netting that is lit by the sun will, because the contrast will suddenly be very bad on the images. It is the same with dirty windows, please clean the outside of your window regularly.
  6. If one has to choose, because the whole width of the street does not fit in the field of view of the camera, then position it to fit the further positioned traffic lanes in the view. So, e.g., instead of fitting half the nearest bike path in, make sure that the bike path and pedestrian walkway on the far side of the road are included.

Installation

  1. Make sure that the camera is well focused (rotating front element in small increments).

  2. Before installation the whole surface of the window needs to be properly cleaned inside and outside around the area where the camera and the shading box will be installed.

  3. The camera cable needs to be covered with black electrical tape to avoid its reflection in the window pane.

  4. The mount needs to be fixed with a sturdy adhesive tape, that is proven to work well between plastic and glass, and that is resistant to heat (otherwise sunshine will slowly melt it away).

  5. The angle of the camera mount needs to be fixed tight so it does not move after installation (do not put any tension on the camera cable, even a tight screw can be moved on the long run if there is a constant tension – you can put a few books under the RPi unit to be able to install the camera higher and/or remove some tension from the cable). At this point check the field of view in and only finalise settings if it is satisfactory.

  6. The shader made out of black carton needs to be installed around the camera, with preferably no gaps between the shader and the glass.