Improving Project Alignment Using a Reference Project

Georeferencing a project is the process of adjusting photos in your project to the geographic location of photos of the same geographical area in a different project. When building a project that overlaps partially or entirely with a different project that will be overlaid on the same map in a client viewer, it is important to ensure that matching areas align properly. This can be achieved by adding the older "base" project as a reference project for the new "target" project. When building the new project, PhotoMesh establishes a correspondence between points in the reference project and the target project, so that the positions of identified features in the target project match the geographic positions of the same features in the reference project.

This tutorial outlines the complete workflow for building a project aligned with a previously built project using the PhotoMesh Reference Project feature.

In this article:

• Step 1: Building the "Base" Project
• Step 2: Starting and Managing Fusers
• Step 3: Referencing the New "Target" Project Based on the "Base" Project
• Step 4: Checking the Results

Data Included in Training Folder (Airwise_Sample_Drone_Data)

These projects' photos are included in two folders:

• 9-30-20 folder contains 162 jpg files of a reconstruction area, captured on September 30, 2020.
• 10-13-20 folder contains 227 jpg files of the same reconstruction area, captured on September 13, 2020.

Download project data   

Step 1: Building the "Base" Project

To build the Base project, do the following:

1. Click Start > Skyline PhotoMesh > PhotoMesh.
2. Click the File menu, and then click New (CTRL+N). The New Project dialog box is displayed.
3. Enter a name and path location for your project, and click OK. 
   
4. In the Add Photos Wizard, click Load Photo Folder.
   
5. Browse to the .\COE - Bixby Fry Creek\9-30-20 folder and click Select Folder. All 162 photos are loaded into the project. A blue information icon indicates that the photos are missing orientation data.
   
6. Click Next.
7. Click Build.
   
8. The Build Parameters dialog is opened. By default, the Output Coordinate System is set to UTM Zone 15, Northern Hemisphere + 0.
   
9. Click Build to start the build. The New build description dialog box is displayed.
10. Enter a build name and click Ok. The PhotoMesh Build Manager is displayed.
11. Select the required fusers (see Step 2), and click Build.
12. When the build is completed, the result will be listed in the Project tree, under Build Outputs. Check its box to display the final output.
    Note:  To open the project in TerraExplorer, click Open in TerraExplorer .
    
    
    

Step 2: Starting and Managing Fusers

PhotoMesh fusers are the worker components of PhotoMesh, which allow you to share the demanding processing requirements of the different build steps (photo preparation, AT, point cloud, mesh model, texture, 3DML/other outputs) between several computers on the same network. When beginning the build process, the PhotoMesh Build Manager application determines what build steps are required and assigns them to the different fusers. PhotoMesh Build Manager and PhotoMesh fusers use the working folder to communicate: to deposit and collect pending tasks, and share information about fuser availability, status and progress. Before beginning the build process, you should start the fusers that will be participating in the build, and set their working folder. More about: Working with Fusers >

Step 3: Referencing the New "Target" Project Based on the "Base" Project

To build the Target project, do the following:

1. Click the File menu, and then click New (CTRL+N). The New Project dialog box is displayed.
2. Enter a name and path location for your project, and click OK. 
   
3. In the Add Photos Wizard, click Load Photo Folder.
   
4. Browse to the .\COE - Bixby Fry Creek\10-13-20 folder and click Select Folder. All 227 photos are loaded into the project.
5. Click Next.
6. This time, click Edit in PhotoMesh.
   
7. In the Project tree, click Reference Projects.
   
8. In the Reference Photos list, click Add Reference Project to add a calculated AT (atResult_v15.sqlite) from another project with overlapping photos, as a reference AT to be used in calculating the Target project's AT. 
   
9. Browse to the build folder of the Base project you previously built (e.g., .\ACOE - Bixby Fry Creek\Base Project\Build_1), select the atResult_v15.sqlite file, and click Open. 
   
10. The Base project's AT is added as a reference project. This ensures that matching areas align properly.
    
11. On the Home tab, in the Build group, click Build. The Build Parameters dialog box is displayed. By default, the Output Coordinate System is set to UTM Zone 15, Northern Hemisphere + 0.
    
12. Click Build.
13. Enter a build name and click Ok. The PhotoMesh Build Manager is displayed.
14. Select the required fusers (see Step 2), and click Build.
15. When the build is complete, the result will be listed in the Project tree, under Build Outputs. Check its box to display the final output.
    

Step 4: Checking the Results

1. Open the project in TerraExplorer by clicking Open in TerraExplorer . The Target 3DML is displayed. Alternatively, open TerraExplorer and click on the Demo Project to open a project with a world satellite map.
   
2. On the Layers tab, select Load 3D Mesh > 3D Mesh layer from file. 
   
3. Browse to the Base project's build folder (e.g., .\ACOE - Bixby Fry Creek\Base Project\Build_1\\outputBuild_1_UTM zone 15, Northern Hemisphere + 5773), select the 3DML and click Open.
   If you started from the TerraExplorer Demo Project, load the Target project's 3DML as well (e.g., from .\ACOE - Bixby Fry Creek\Base Project\Build_1).
4. Note that both 3DMLs from different times are loaded into the project, one on top of the other. On the Analysis tab, select > Swipe > Swipe Layers to swipe and compare the 3D mesh layers.
5. Move the slider to compare the results and to confirm the two models are properly aligned with each other.