Every ArcGIS Drone2Map project includes a detailed processing report that displays the results of the block adjustment. Block adjustment is the process of computing an adjustment or transformation based on the internal relationship between overlapping images, control points, a camera or sensor model, and a digital elevation model (DEM). After performing a block adjustment, it is necessary to review the results of the adjustment and assess the quality of the control points (ground control points [GCPs], tie points, and checkpoints) used in the adjustment.
To access the report once the initial processing step is completed, on the Home tab, in the Processing section, click Report. You can also access the processing report at any time in the project folder in PDF and HTML format. The processing report includes the following sections.
Overview
The Processing Summary table provides basic information about the project, such as the camera used and the project's overall scope. The fields in the Processing Summary table are described below:
| Field name | Description |
|---|---|
Project Name | Name of the ArcGIS Drone2Map project. |
Processed On | Date and time the report was generated. |
Camera Model | Drone camera model used in processing. |
Mission Size | Total size of the mission images in gigapixels |
Coverage Area | Size of the project area used in processing. The units are in hectares or acres. |
Mean Ground Sampling Distance | Average ground sampling distance for all images in the image collection. The units are listed in meters or feet. |
Processing Time | Total time elapsed to process the project. |
Quality Checks
The Quality Checks section provides a synopsis of the settings used for the block adjustment process and the quality of the adjustment. The fields in the Quality Checks table are described below:
| Field name | Description |
|---|---|
Calibrated Images | Number of images that are successfully involved in adjustment, so that image exterior orientation parameters and interior orientation parameters are accurately optimized. This check is passed |
Calibrated Focal Length (Initial, Adjusted, Optimized) | Initial camera focal length value compared to adjusted focal length value with the difference shown as a percentage. A difference less than 25% means camera calibration converges to an optimized value close to input focal length. Otherwise there might be blunders in input focal length or pixel size. |
Tie Point Mean Reprojection Error RMSE | The average root mean square error (RMSE) across all project tie points in pixels. For most nadir frame camera cases, this value should be smaller than 0.5 pixel. For oblique cases, less than 1.0 pixel is acceptable. If the tie point mean reprojection RMSE is larger than 1 pixel, it may mean that camera calibration is not accurate. For example, camera might be a rolling shutter type, but adjustment doesn’t enable rolling shutter mode. Or the initial input camera focal length, or pixel size, is not correct. |
Mean Number of Tie Points per Solution Point | The ratio between number of tie points and number of solution points. It records the average number of images that can observe one solution point. It reflects the configuration of the flight. An ideal image collection should have a value larger than 3. A mean number of tie point observations less than 2.5 usually means the overlap between consecutive images is not sufficient. |
Ground Control Points Used | The number of ground control points used within the project. The average root mean square error (RMSE) of all ground control points is shown in the XY and Z directions. This check is passed |
Checkpoints Used | The number of check points used within the project. The average root mean square error (RMSE) of all ground control points is shown in the XY and Z directions. This check is passed |
if 95% or more images are calibrated. There might be blunders in the input images or camera parameters if less than 50% images are calibrated. For example, more than half of the images are covered by water body.Image Adjustment
The Tie Point Reprojection Error graphic displays a chart of all the tie points generated for the project and the average reprojection error in pixels from the initial calculated positions.
The Orientation Uncertainties table lists the maximum and minimum standard deviation of the exterior orientations (X, Y, Z, Omega, Phi, Kappa) that were computed for project images after the Adjust Images step. The standard deviation gives an indication of the reliability of the optimized parameter. Typically, the quality of the adjustment increases as the standard deviation approaches zero. A value of zero is expected when the parameter is fixed in processing options. The fields in the Orientation Uncertainties table are described below:
| Field name | Description |
|---|---|
X | Solution point shift in the X direction from the initial position. The units are feet or meters. |
Y | Solution point shift in the Y direction from the initial position. The units are feet or meters. |
Z | Solution point shift in the Z direction from the initial position. The units are feet or meters. |
Omega (degrees) | Image rotational angle shift of the camera's x-axis. The units are decimal degrees. |
Phi (degrees) | Image rotational angle shift of the camera's y-axis. The units are decimal degrees. |
Kappa (degrees) | Image rotational angle shift of the camera's z-axis. The units are decimal degrees. |
Initial vs Adjusted Image Positions
The Initial vs Adjusted Image Positions graphic shows a representation of the GPS deviations for each image before and after block adjustment. Blue points indicate the initial position of the images from the GPS, and green points indicate the GPS location as a result of adjustment. When viewing this graphic, assess the directional shift of the images in your image collection to evaluate systematic error in the adjustment. The fields in the Initial vs Adjusted Image Positions table are described below:
| Field name | Description |
|---|---|
dX | Image shift in the X direction from the initial position. The units are feet or meters. |
dY | Image shift in the Y direction from the initial position. The units are feet or meters. |
dZ | Image shift in the Z direction from the initial position. The units are feet or meters. |
Cross Matches
The Cross Matches graphic indicates the level of connection between images. A link with a dark color indicates a larger number of tie point sets and a stronger connectivity between the images. Identify areas in your image collection where tie points are sufficient or lacking, and use this information to add control points or overlapping images if necessary.
Image Overlap
The Image Overlap graphic is a static map of the overlap between images. Higher numbers of overlapping images produce higher accuracy for three-dimensional ortho products. You can use this graphic to identify areas in your image collection that may require additional overlap, or to better understand the accuracy of your adjustment.
Camera Parameters
The Camera Parameters section contains a Summary Table with details of the cameras used in the project.
The fields in the Summary Table are described below:
| Field name | Description |
|---|---|
Camera Model | The camera model information read from the image metadata. |
Serial Number | The serial number for the camera read from the image metadata. |
Images Used vs Total | How many images from the camera were used in processing versus the total number of project images from that camera. |
Acquisition Date | The date the images were captured read from the image metadata. The latest date will be used if multiple flights are present. |
The Optimized Camera Parameters table displays camera calibration information used for the adjustment. The camera calibration parameters can be modified in the Edit Camera Parameters pane by using the Edit Camera button on the Flight Data ribbon.
The fields in the Optimized Camera Parameters table are described below:
| Field name | Description |
|---|---|
Camera Model | The camera model information read from the image metadata. |
Principal Point (mm)- X, Y | The principal point is a point on the image plane where a line from perspective center (camera lens), perpendicular to the image plane, intersects the image plane. The X direction is parallel to the direction of image rows. The Y direction is parallel to the direction of image columns. |
Distortion Coefficient - K1, K2, K3, P1, P2 | Lens distortion parameters, defined by the Brown-Conrady Model. D.C. Brown, Close-range camera calibration, Photogramm. Eng. 37 (6) (1971) 855–866. |
Focal Length (mm) | Initial versus adjusted camera lens focal length in millimeters. The initial values are derived from the camera database when you load project imagery. The difference between initial versus adjusted is displayed as a percentage. A difference less than 25% means camera calibration converges to an optimized value close to input focal length. Otherwise there might be blunders in input focal length or pixel size. |
Geolocation Details
The Geolocation Details section of the processing report provides adjustment details on any control points that were used in the project.
The Ground Control Points (GCPs) and Checkpoint tables show an overall summary of the project's control points. It is only listed in the report if you used control in the adjustment. Each point is listed in the table as its own field along with adjustment statistics for the point. The fields in the tables are described below:
| Field name | Description |
|---|---|
Name | Name of the ground control point used in the adjustment. Statistics for each point include its shift after adjustment from its initial X (dX), Y (dY), and Z (dZ) position in meters. Projection error for each point is listed in pixels. Status lists the number of valid versus total image links used for that ground control point. |
Survey Accuracy (m)- XY, Z | The accuracy by which the GCP was surveyed. The initial accuracy values when first importing the control points. |
Residual Error (m)- X, Y, Z | Difference of the observed versus predicted location of the point measured in meters. |
Reprojection Error (pixels) | Difference between the initial versus reprojected position of the point. |
Used/Linked | Number of links used during the adjustment (not dropped) versus the total number of links created. |
Control Quality Check Icon | This check is passed |
Project settings
The project settings section of the processing report includes information about the system the project was processed on, coordinate systems used in the project, project resolution, and whether any preprocessing was used. These sections are described further below.
The System Information table lists the system hardware and operating system information for each project. Hardware information is displayed as the system's CPU, RAM, and GPU. For more information about supported hardware in ArcGIS Drone2Map, see ArcGIS Drone2Map system requirements.
The Coordinate Systems Information table lists the coordinate systems used in the project. The table is divided into the coordinate system used for the images, project, and ground control points. If there are no ground control points in the project, that field will not appear.
The Pre-Processing table provides an answer to whether preprocessing adjustments were used in processing of the project. A Yes or No is provided for each of the preprocessing options.
Processing Options
The General Options table lists the user-defined settings used in the adjustment process. The point cloud density and project resolution are defined in the processing options and default to different levels depending on the template in use.
The fields in Adjust Images Options are described below:
| Field name | Description |
|---|---|
Fix Image Locations | Indicates whether the Fix Image Location for High Accuracy GPS (RTK and PPK) option is enabled. If enabled, the GPS information from the image metadata will be used in an unmodified state during the adjustment step. |
Use Image Orientations | Indicates whether the Use Image Orientations option is enabled. If enabled, the orientation parameters from the image metadata will be used during the adjustment step. |
Initial Image Scale | The image scale used to extract feature points for adjustment |
Refine Adjustment Scale | The image scale used when the refine adjustment option is enabled |
Matching Neighborhood | Size of the neighborhood used to find tie points during adjustment |
Rolling Shutter Correction | Indicates whether rolling shutter correction was applied during processing. If enabled, the adjust images step will use rolling shutter correction to reduce distortions and inaccuracies caused by rolling shutter cameras. |
The 2D product Options section of the processing report provides a summary of which 2D products were enabled for processing on the project.
The 3D product Options section of the processing report provides a summary of which 3D products were enabled for processing on the project.