ReCap Photo

Photogrammetric restitution must be first created. This is a process over which we have no control. It’s carried out automatically through Autodesk ReCap servers. You just have to select the photos of the model

Quick tip: This process takes a long time to get the model. It may take 8-24 hours to be available.

Open ReCap Photo and click on Object. Then, click on Add photos and choose them. Go to Create and, in the Create Project pop-up window, name the project and choose its location in the Cloud Project folder.

Recommendations for taking pictures:

• They must be taken using the same camera lens to keep its focal length. If you have a multi-camera phone, you will have to use the same camera lens to take the photos.
• Take photos on cloudy days to avoid shadows and loss of information. If it is not possible, take them at noon when the sun is at its highest point of elevation (zenith).
• Have a moderate distance from the object.
• At least 20 photos are needed.
• Keep relation with the previous picture, that is, have common areas between one photo and another.

The 3D model obtained corresponds to a mesh, not a point cloud. It must be transformed into a point cloud if you want to export it to Revit or Advance Steel. For this process, CloudCompare will be used.

If there are areas in the model that did not look good, it is due to a lack of information.

The steps are the following:

• Cleaning: we proceed to erase everything that is not part of the model, such as the ground, trees and white areas by means of the Selection tool.
• Rotate: Place the main face on the X axis with Transform model.
• Scale: Size the model to the actual measurements with Set scale & units
• Export: Save the model in FBX format with Export model.

CloudCompare

To create the point cloud, open CloudCompare and load the FBX model. Then, click on mainMesh to enable some options

Click on Sample points on a mesh and accept the default options. With the previous step, you can set the number of points you want to extract from the mesh.

The point cloud already appears and is called mainMesh.sampled, below mainMesh. It must be saved in e57 format. This format is compatible with Autodesk ReCap.

ReCap

Open ReCap and go to New Project. Click on Import point cloud, name and choose its location where it’s going to be saved. Select files to import and click on: Import, Index and Launch.

The point cloud must be saved in .rcp format. This format is compatible with Revit and Advance Steel.

Regard 3D

This is a free and open source software to make 3D models from photographs. It is easy to understand and has a minimalist interface.

It can be used to create the point cloud and also the surface of the model.

Although the steps using this software are not shown in the video, the process would be as follows:

• Create a new project through: File > New Project. Select the photos.

• Set the Parameters of Keypoint sensitivity to 0.0005 and the Keypoint matching ratio to 0.7.

• Matches between points:

• Parameters of triangulation:

Points returned: a total of 75.137. The photos were taken with a Samsung Galaxy S8. An attempt was made to create another model of the same work, but in this case the photos were taken with a Redmi Note 8 Pro. The time to compute the matches exceeded 55 minutes and the total number of points was over 240.000. Therefore, it was decided to continue with the Samsung photos

The model is shown:

• Parameters to densify the point cloud:

• Process completed:

• Creating a surface from the point cloud: