Make a backup copy of your calibration file in the event of hardware failure. You can always source a replacement tablet should there be a problem.
Before you get started make sure there is a proper calibration file loaded. If not, it will affect your results. You can easily check or correct this by going to the "Info" tab and choosing the right calibration file for the unit. This must be done prior to starting to capture data. Customers should use the X_YHOU.cal file if they have one and the X_Ytemp5.cal if they have a "temp" file (initial naming convention). Contact support your file is missing.
When you begin scanning, remember to consider the following when choosing your starting point:
- Have good geometric features such as intersecting planes and objects.
- If traversing around an object, start at the logical beginning and the end of a closed path.
- Begin at point you can come back to if you think you will need to pause.
Make sure there aren’t gaps in the scene such as large spaces between vessels otherwise the system will lose tracking. Add a feature to the scene such as a trash can or chair to bridge the gap. Capturing floors, ceilings and walls can be very problematic if they are blank or reflective type. Tracking depends on geometric features in the scene. You can improve results by panning along the floor/wall or wall ceiling edge. Adding targets will also allow better tracking. This is particularly important when the runs are long, for example a long piping run, and the tracking features are few.
If possible, transparent or semi-transparent surfaces should be covered before scanning. The reason is that the infrared pattern from the sensor could get distorted when it goes through glass or similar materials, resulting in non-accurate readings. If possible also cover wide-area reflective surfaces. Small chrome handles etc. are perfectly fine but large mirrors etc. could be a problem.
When imaging an area of interest, it is recommended to traverse the area initially with the goal of creating as few frames as possible. If higher detail is needed on a particular spot, or if capture of a hidden or shadowed area is needed, do an initial traverse first without details, then going back to the particular areas of interest to fill in the details. This may also be separated into several capture sessions using the append feature.
Keeping the scanner orthogonal to the main surface has a positive effect on accuracy. Scanning at an angle against surfaces usually results in reduced accuracy caused by increased drift errors. Holding the DPI-7 as orthogonally as possible will help eliminate drift errors.
Getting close to objects in the scene generally leads to more accurate data but at an increased risk of tracking loss, depending on the amount of surface geometry and texture of the captured object. Getting far away generally includes more features and textures into the field of view and hence leads to more stable tracking but it can introduce distortions beyond 2m. Therefore users should always get as close as possible to get accurate results but as far away as necessary to guarantee stable tracking.
DP files are highly compressed. A size of 30 MB or more is considered huge. When DP files are loaded into memory, the space requirement increases 25 fold; 10 MB of DP file expand to about 250 MB of memory allocated internally for all the data. A good rule of thumb on size is to try to maintain the DP file size at or below 20 MB.
If you must scan a scene that will exceed the file size and practical scene size limitations, break the scene into smaller overlapping scenes. Use a tool like Cyclone Register (cloud-based registration) to joins scenes together.
Target picks should be from frames that are somewhat close, and with targets close to perpendicular to the view. Avoid picking targets at the borders of a keyframe. These recommendations will improve accuracy of the target pick. Picking targets that are far away, at high angles, or at the very borders of a keyframe, will result in less than optimal results.