Calibrate - PIX4Dmatic

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Calibrate

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Point cloud

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Mesh

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DSM

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Orthomosaic

Calibrate

 
Access:
  • Click Process processing_options.png.
  • On the Menu bar, click Process > Calibrate...

It allows users to change the following processing options:

Calibrate.png

Calibrate processing options.

Calibration templates

These are the default calibration templates available in PIX4Dmatic. We strongly recommend using these to process your project:

Calibration Template Description
Large scale and corridor (Default)

Calibration pipeline: Scalable standard.

Typical input: Nadir images.

Processing speed: Faster.

Application: Generate 2D and 3D reconstructions of a relatively large area of interest with images captured above the area of interest.

Map

Calibration pipeline: Standard.

Typical input: Nadir images.

Processing speed: Slower.

Application: Generate 2D and 3D reconstructions of an area of interest with images captured above the area of interest. 

Model

Calibration pipeline: Standard.

Typical input: Oblique images.

Processing speed: Slower.

Application: Generate 3D reconstructions of an object of interest with images captured around the object of interest.

Flat scene and low texture

Calibration pipeline: Low texture planar.

Typical input: Nadir images.

Processing speed: Slower.

Application: Generate 2D and 3D reconstructions or an area of interest that contains relatively homogenous textures and relatively flat terrain, like an agricultural field, with images captured above the area of interest.

PIX4Dcatch

Calibration pipeline: Trusted location and orientation.

Typical input: Terrestrial imagery.

Processing speed: Faster.

Application: Generate 2D and 3D reconstructions or an area or object of interest with images captured around the area or object of interest with PIX4Dcatch.

Calibration pipeline

Allows selecting how the camera's internal and external parameters are optimized.

  • Scalable Standard (default): This calibration pipeline is a sequential pipeline that enhances image calibration for large datasets and fast processing.
  • Standard: This calibration pipeline is similar to Scalable Standard, but it is more robust, requires more processing time, and uses more PC resources.
  • Trusted location and orientation: This calibration pipeline is intended for projects with accurate relative location and IMU data; for example, images taken with PIX4Dcatch in an indoor or outdoor setting or images from RTK or PPK drones or devices. All images must include information about the camera's initial position and orientation.
  • Low texture planar: The calibration pipeline is intended for aerial nadir images with accurate geolocation and homogeneous or repetitive content of relatively flat terrain.

Image scale

Defines the image size at which keypoints are extracted. It is possible to select:

  • 1 (Original image scale): This is the recommended Image scale.
  • 1/2 (Half image scale): This can be used to speed up processing and for cameras with very high resolution.
  • 1/4 (Quarter image scale): This can be used to speed up processing to get a fast overview and assess the completeness of the project.
  • 1/8 (Eighth image scale): This can be used to speed up processing to get a fast overview and assess the completeness of the project.
 
Tip: Reducing the Image scale will usually result in a slightly reduced accuracy because fewer keypoints will be extracted. On the other hand, it can help to calibrate datasets with blurry images or datasets containing homogenous areas. We recommend reducing Image scale:
  • To speed up processing.
  • To get a fast overview and to assess the completeness of the project.
  • For datasets containing blurry images.
  • When processing datasets of flat and homogenous or repetitive and complex areas, such as trees, forests, and fields, because it can result in a higher number of calibrated images.
 
Information: Keypoints are computed with multiple image scales, including all image scales between the selected image scale and 1/8 image scale. For example, if 1/2 is selected, keypoints are computed with 1/2, 1/4, and 1/8 image scale.

Keypoints

Allows to set up the number of extracted keypoints.

  • Auto (Default): PIX4Dmatic automatically determines the optimal number of keypoints to extract.
  • Custom: Directs PIX4Dmatic to identify a specific number of keypoints, image content permitting.
    • Number of Keypoints: The targeted number of keypoints to be extracted per image.
 
Information: When extracting keypoints, a score is assigned to each keypoint. Based on this score, the best keypoints are selected.

Internals confidence

Defines how much the camera parameters (internals) can be recalculated and adjusted during the project calibration:

  • Low (Default): Optimizes all the internal camera parameters.
  • High: Forces the internal parameters to be close to the initial values. We recommend using it when:
    • The difference between the initial and optimized camera parameters is higher than 5%.
    • The calibrated project is warped or curved.

Use depth maps (Optional)

 
Important: Available only with PIX4Dcatch projects that contain LiDAR depth maps.

Use depth maps: When enabled, the depth maps generated with PIX4Dcatch are used for better calibration.

Reoptimize cameras

 
Access: In the menu bar, click Process - Reoptimize...

This process is used to reoptimize already computed internal and external camera parameters. It can be used when changes to GCPs are applied after the Calibrate step is completed.

 
Tip: Using the Reoptimize cameras option reduces the processing time after applying changes to GCPs.

Such changes can be:

  • Adding GCPs marks.
  • Changing the position of existing GCPs marks.
  • Removing GCPs with marks.
 
Important: The project is reoptimized only when all other Calibrate options remain unchanged. For example, when changing the Image scale or Keypoints, the Calibrate step must be re-run in place of Reoptimize.

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