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Calibration
Calibration is the first step of every project. Default settings are available depending on the source of the dataset and are generally the best place to start. Additionally, there are several options to choose from, enabling customization to suit a dataset with a particular set of variables or needs. Templates, pipelines, Image scale, Keypoints, and Internals confidence are available for adjustment in this important step. This article will define each to inform of its function and help aid selection when needed.
- Click the Process
icon.
- From the Menu bar, click Process > Calibrate...
IN THIS ARTICLE
Calibration Template
Calibration Pipeline
Image scale
Keypoints
Internals confidence
Automatic ITPs
Use depth maps (Optional)
Reoptimize cameras
Calibration Template
PIX4Dmatic Calibration dialog.
A template is a set of predefined settings to handle a particular type of dataset.
| 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 large project area using aerial images. |
| Map |
Calibration pipeline: Standard. Typical input: Nadir images. Processing speed: Slower. Application: Generate 2D and 3D reconstructions of an area of interest using aerial images. |
| Model |
Calibration pipeline: Standard. Typical input: Oblique images. Processing speed: Slower. Application: Generate 3D reconstructions of an object with oblique imagery |
| Flat scene and low texture |
Calibration pipeline: Low texture planar. Typical input: Nadir images. Processing speed: Slower. Application: Generate 2D and 3D reconstructions of an area of interest that contains relatively homogenous textures and flat terrain. Images should be captured above the area of interest. This template should be used for agricultural applications. |
| PIX4Dcatch |
Calibration pipeline: Trusted location and orientation. Typical input: Terrestrial imagery. Processing speed: Faster. Application: Generate 2D and 3D reconstructions of an area or object of interest. Images should be captured around the area or object of interest with the PIX4Dcatch mobile application. |
| Interior scene |
Calibration pipeline: Trusted location and orientation. Typical input: Terrestrial imagery. Processing speed: Faster. Application: For interior projects captured with the PIX4Dcatch mobile application and calibrated with ITPs. |
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.
- 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.
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.
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. Recommended 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)
Use depth maps: When enabled, the depth maps generated with PIX4Dcatch are used for enhanced calibration.
Automatic ITPs
Intersection Tie Points (ITPs) are designed to be used in man-made environments including both interior and urban scenes. They are a type of machine learning object that uses intersecting linear features to generate a tie point. The default is set to off, however, when enabled ITPs can be used to help calibrate a scene. To learn more please click here.
Reoptimize cameras
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.
Such changes can be:
- Adding GCPs marks.
- Changing the position of existing GCPs marks.
- Removing GCPs with marks.
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