Using Survey Control Targets In Dot3D

Using Survey Control Targets In Dot3D

(For a video tutorial, click the link here)

When creating a scan with Dot3D, you may want to use known Survey Control points, to increase the accuracy of the scan, or to fit it into a coordinate system

To begin, when creating your scan, you will want to use at least 3 April Tag Targets in your scene, preferably separated across the scan, with good spacing between them

When you have your tags set up, you must determine their XYZ coordinates in a local/global system - This information can be obtained from several sources, such as a Surveying total station, a gnss or rtk receiver, a separate laser scan, a drone, a survey map of your space, or a 2D/3D cad model of the building/area. This information can be applied post scan, before optimization

After you finish scanning, there are two ways to enter your coordinate values into Dot3D

The first method is to enter the coordinates for each tag manually. additionally, you can load a control file with columns for Target ID and XYZ position. To start either method, first press "Targets"



If you are entering each target's position manually, you can pull up on the bottom right tab to access the information for every target





If you are using a Control File, instead press the "Load Control File" button near the top left of the screen



From here, press "OPEN CONTROL FILE...", and select the file you wish to use



With your file loaded, you can select the "Control Targets" number in blue to see a preview of your file. This also serves as a guide to what formatting you should be using in your own file - First column April Tag, second column X, third Y, and finally fourth for Z. A simple file like this can be created with something like excel, or any text editor, and saved as a txt file





Finally, make sure you have the correct units selected. If you need to change your units, this can be done with the dropdown box in the top left. When everything looks good, you can press "IMPORT" to finish loading in your file





Now make sure you press the "Fit Control Targets" before you optimize



When your ready to optimize, first press the "Optimize" button on the top bar



This should pull up a window with various different check boxes. Everything you want should be checked automatically, including using your control target points to help with optimization. Leave everything checked, and then press "OPTIMIZE SCENE"



After optimization is finished, you should notice improvements with the accuracy of your scan, and overall cleaner data. Post optimization, you can check how well your target points align with the April Tags in your scan. To do this, first press on "Targets"



Now, press on "Fit Control Targets" twice. This will give you a target fit summary





You can now export/save your scan. When doing so, make sure you have "Control Targets" checked, so your data fits into the coordinate system you used when creating the control targets







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