Referencing – An important step made more efficient
Referencing is a key concept in PhotoModeler. Basically, PhotoModeler needs to know when objects appearing in multiple photos are views of the same real-world object (i.e. a building corner appearing in two different photos). PhotoModeler uses referenced points to generate the base 3D model. Point referencing can be done manually or, in some cases, automatically. Other objects such as cylinders, edges, and NURBS curves are also manually referenced.
Since all projects require some manual referencing here are some tips to help speed things up:
- Manual referencing involves opening a ‘source’ and a ‘destination’ photo. You can open these photos directly using the referencing toolbar’s ‘Source photo’ and ‘Destination photo’ list boxes. You then select points in the ‘source’ photo and select the same points in the ‘destination’ photo as PhotoModeler highlights them one by one.
- The ‘Auto-drive’ facility can really speed up the process of finding the matching point in the destination photo. For auto-drive to work, the photographs need to be oriented (project must have been processed once), so your first goal is to get all of your photos oriented by marking and referencing six to ten points on each photo.
- Once PhotoModeler has calculated the cameras’ 3D locations (i.e. photos are oriented), ‘auto-drive’ will show you a ‘helper-line’ in some photos and will drive the cursor to the correct location in the other photos. No more searching for the desired point!
- To quickly switch the source or destination photos, you can use the right-click referencing menu and select ‘Make source’ or ‘Make destination’.
- During referencing if it is difficult to make out the destination point you can press the ALT key to zoom in.
- With projects of three or more photos, you often need to reference objects on more than one photo. The auto-advance cursor helps you step through all the ‘destination’ photos you need.
- For quickly creating points you can use a special referencing sub-mode called ‘Mark on source photo’. This sub-mode allows you to mark new points on the source photo and then immediately reference them on the destination photo without leaving referencing mode. This is useful when adding points to ‘touch up’ an area.
These are just a few tips to help you with manual referencing. In the help file and user manual you can learn about other tools such as Automatic Referencing and Point Weld.