ContextCapture User Guide

Block

A Block item manages a set of input data used for 3D reconstruction: photos and/or point clouds. The block item manages photos and their properties (photogroup properties: sensor size, focal length, principal point, lens distortion / pose: position, rotation), and optional point clouds.

Based on the block item, one or several reconstructions can be created.

A photo can be used for 3D reconstruction if it is complete. A photo is complete if it fulfills the following conditions:

  • Its image file is in a supported file format (see Input photograph file formats) and is not corrupted,
  • Its photogroup properties and pose (see Useful concepts):
    • Are known accurately,
    • Are consistent with the ones of other photos.

To achieve the two above conditions, photogroup properties and photo poses must result from a joint optimization of the different photos of the block. The set of consistently optimized photos constitutes the main component of the block.

You can obtain a set of complete photos by two main methods:

  • By adding photos to the block, with only a coarse guess of photogroup properties, and then by using ContextCapture 's aerotriangulation to estimate complete and accurate photogroup properties and photo poses.
  • By importing photos with complete and accurate photogroup properties and photo poses (e.g., from third-party aerotriangulation software) from an XML file (see Import blocks).

Block item interface

The block item is defined by the following properties:

  • Photos: the photos you imported or added, and their associated photogroup properties and photo poses (computed by Aerotriangulation, or imported).
  • Point clouds: imported from point cloud files.
  • Survey Points: Control points or user tie points entered manually, or imported. Survey points are optional.
  • Automatic Tie Points: automatically extracted by ContextCapture , or imported.
  • Positioning Constraints: position/orientation/scale priors based on user tie points.
  • Additional data additional knowledge on the acquisition used to help aerotriangulation.
  • List of reconstructions based on the block.

The block General tab manages the block dashboard and block reconstructions.

For convenience, a block with some known 3D data (photo poses, control points, point clouds) can be displayed in 3D in the 3D view tab.

For a block, the following features are proposed:

Note: Once a reconstruction is created, properties are read-only. You can clone the block to get a new editable block initialized with the same properties.