The Handheld is a versatile device that can be used in a wide variety of conditions. However, if the user wants to get the best sizing accuracy possible, we recommend following the guidelines outlined below.
Do not use the device too close to the crop
Please ensure the distance between the device and the crop is between 500-1000 mm (waist level).
Do not use the device on stacked crop
When there are multiple layers of crop, the device will likely detect crop in the bottom layers that are partially visible. This will cause an overestimation of undersized crop from the sample, thus biasing the results. Please see below an example of the issues caused by crop stacking.
Avoid clustering the crop
If the crop is too clustered (i.e. without gaps in-between them), the sizing accuracy can be affected to some extent (see the first image below). This is because, in particular conditions, clustering may not only hinder the correct detection of the crop's contour but it may also prevent some crop to lay completely flat on the surface, thus preventing the camera to capture the full length of the crop (see the second image below - the crop in red will have less accurate measurements).
Take snapshots with the tablet on a 90° angle
Try to take snapshots on a 90° angle as much as possible (please see the image below).
Ensure good lighting and background contrast
Please ensure there is good lighting so that the crop is visible. Also, please ensure there is a good contrast between the background and the crop being scanned. If they have similar colours, the system may struggle more to identify the contours of the crop. In some cases, if necessary, we suggest adding a bag or a board underneath the crop to improve contrast (see an example below).
