As opposed to using geo-registered control points, which were measured via GPS or in relation to a global coordinate system, in some projects it is only necessary to understand the relative distances and derive a relative alignment of captured scans one to another. While this is technically possible, NavVis currently does not support this as a full workflow within NavVis Products.
NavVis IVION Processing
When processing data with NavVis IVION Processing, control points which were captured during a scan will not be considered when no control point file is provided during the setup of a Processing Task. Therefore, post-processing with non-measured control points is not supported and datasets processed with common non-measured control points will not be aligned as a result.
After transferring the processed data to IVION the datasets will need to be manually aligned.
Desktop Processing Software
When processing data on a local workstation, control points which were captured during a scan will not be considered when no control point file is provided in the SiteMaker or via the command line.
There is an additional command line tool called nv_anchor-dataset-alignment available, which can be used to create an xml-formatted alignment file. It is documented in our documentation. This xml-alignment file can then be used to align the processed point clouds to another or merge them into one. The command line tool nv_cloudtransform can be used for this as documented here.
This workflow is independent from IVION, therefore, xml-alignments can not be imported into IVION. There, point clouds need to aligned manually once full datasets are imported.
Written in February 2022