Capturing a Scan
Site captures are organised according to a hierarchy of projects, scenes, and scans. For example, a project might represent the entirety of a building. Each scene within that project might represent one floor within that building. Each scan provides a single time-stamped capture of that scene on a particular day.
When capturing data of a scene we refer to this as "scanning" the scene. A scan is one continuous walk through the entire scene. Sensori Capture is able to stitch together multiple separate recordings, but only if they contain significant amounts of overlap with each other.
Order of operations
Ensure there is a memory card and charged battery in the camera before going to the site
Locate surveyed control points if those will be used
Place the origin plate horizontally at a desired 0,0,0 position or place control point targets over surveyed control points
Distribute scale plates around the scene. They do not need to be horizontal, so leaning them against a wall can improve visibility.
Turn the camera on
Set the aperture and focus
Hit the record button once, the red recording circle will appear on screen
Slowly walk through and capture the scene, making sure to regularly turn around a full 360 degrees
Take care to record each target more than once and try to get within less than 1 metre of the target.
Walk back to where you started if possible
Hit the record button to stop, the red recording circle will disappear
Collect targets as required
Upload videos from camera and control points csv file if used to the Sensori website
Camera check
Before you begin, ensure the camera has the memory Card and battery installed. You can do this by opening the card slot and battery housing.
Turn the camera on and ensure there is going to be sufficient battery for the full scan.
Check camera settings against the list provided above if they might have been changed.
Check focus and aperture
Once the camera is turned on we must set the focus and aperture. These settings will not be altered at any point during the scan.
The aperture should be set at F2.0 and this is done by manually adjusting the aperture dial on the fisheye lens.
For focus checks we will adjust this manually as opposed to using an auto-focus system. The focus distance should be set as shown in this image, but we recommend looking at the focus peaking provided in the camera's live view. To do this:
Stand about 2 metres from an object in the scene and point the camera at the object
Move the focus ring left and right, you will see highlighted "peaks" change as you do this
During this movement you want to look for a point where there are the most "peaks", which are shown as highlighted areas, around the object
Once you have found the point where there are the most "peaks" leave the focus ring in that position
The focus is now set for the scan
Walk the site
When capturing there are a few guidelines to consider:
Don't move faster than a slow walk, about a third your usual pace
Don't swing the camera faster than you would a cup of liquid
Each time you pass a target (Origin plate, scale plate, or control point), point the camera at the target and move it left and right
Try to "weave" through the site, crossing back over spaces you have walked through
Occasionally turn around a full 360 degrees to ensure you capture in all directions. This is very important to ensure your capture is fully connected and has low drift error
If a space becomes narrow, such as a tight corridor or doorway, then slow your pace further
If there are areas of interest (pipes, cables, etc) then get closer to these areas and slowly move the camera around them to capture more detail
Any area that you don't walk through will not be reconstructed well, so be sure to walk throughout the whole scene that you want to capture. It doesn't matter where you start, but it's a very good idea to walk back to where you started before you end the capture, and try to visit each area more than once
Example clip showing the recording of a control point marker
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