DEM Accuracy Analysis

Functional Overview

The elevation accuracy of the digital elevation model is analyzed by the checkpoint method.

Usage

1. ClickTerrain > DEM Accuracy Assessment, the DEM Accuracy Assessment interface will pop up:

1. Click Add DEM file, select the digital elevation model file be analyzed (currently only .tif format);

2. Click Add Check point to add a checkpoint file (only .txt format is supported);；

3. Click Execute Analysis ,set parameters to execute precision assessment and assessment result statistics (corresponding to checkpoints) number, number of gross error points, gross error rate, average error, medium error, tolerance);

4. Click the export report , set the relevant information to export the precision assessment report.

Import DEM

Add the digital elevation model file to be analyzed, currently only .tif format files are supported.

Import checkpoint

Add checkpoints. Checkpoints can be derived from GNSS measurement, photogrammetry, existing results (topographic maps, digital elevation models, etc.) Reference System.

Analysis

To perform an accuracy analysis, it must be performed after adding the DEM file and adding the checkpoint file.

Analysis Settings

• RMSE formula: The formula for calculating the error in elevation.
  • High precision:
    
  • Equal precision:
    
    In the formula, M is the error in the result, n is the number of detection points, and is elevation difference.
• Tolerance: Error tolerance

Note: ①Usually, in the case of high-precision detection, use 2 times the allowable medium error as the tolerance, and use formula 1 to calculate the result medium error; in the same precision detection, use the. The allowable middle error is used as the tolerance, and the middle error of the result is calculated by formula 2. Errors within the tolerance range participate in the precision statistics, and errors beyond the tolerance are regarded as gross errors. ② After the analysis is performed, the analysis status of each DEM file,indicates the digital elevation model error The gross error rate is less than 5%,indicates that there is no detection point within the range of the digital elevation model,means that the gross error rate of the digital elevation model is greater than 5%.

Export report

Export the error detection report in elevation.

Export information settings

• Project Name: The project name.
• scale: Scale bar.
• Inspection Method: The detection method.
• Unit: Unit.
• Instrument Name, Model: Instrument name, model.
• Instrument Number: The instrument number.
• Output Path: The report save path, currently only supports .html format.