Feature Extraction
The feature extraction module is used for vectorizing elements in the scene. This module provides functionalities for extracting road curbs, intersection lines, building contours, contours from models, toe lines, intersection drawing, and vector extraction using SAM. The objects of vectorization in this module are buildings or roads. When any function of this module is activated, if there is no relevant layer, the software automatically adds a corresponding layer.
Extract Road Curb
Activate the semi-automatic curb edge vectorization function
- Click the left mouse button for the first time to determine the search box position, ideally near the middle of the curb face.
- Click the left mouse button for the second time to determine the search direction, specifying the forward direction of the curb, and start the operation.
- The software automatically extracts the upper and lower edges of the curb and adds them to the current layer.
- (Optional) Click the toolbar's undo button to undo the last extracted edge line.
- (Optional) After the function is activated, a feature file will be generated in the same directory as the image. Click on the image with the mouse to automatically recognize the vector from the image.
Parameter Settings
- Length (meters): The length of the search rectangle box, default is 0.5 meters. The larger the value, the faster the search speed, but too large a value may cross over two disconnected road sections.
- Width (meters): The width of the search rectangle box, default is 0.2 meters. It should cover the curb area but not be too large.
- Height (meters): The height of the search rectangle box, set according to the curb height to be extracted. Slightly larger than the curb, adjust using the height indicator line.
- Curve Angle (degrees): The degree of curvature in the direction of the curb. For curved roads, the default is 30°.
Extract Building Footprint
Activate the semi-automatic building contour vectorization function
- Click the left mouse button to select the area where the contour is to be extracted.
- Double-click to end the area selection and automatically extract the contour line of the selected area.
- The contour line is vectorized into polylines and added to the building layer.
- (Optional) Click the toolbar's undo button to undo the last extracted contour line.
- (Optional) Click the toolbar's redo button to re-add the last undone contour line.
Parameter Settings
- Point Source: This parameter defines the type of volumetric measurement data source.
- from File (default): Uses points within the specified range from the point cloud file. The speed is relatively slow, but the calculation result is stable.
- from Loaded: Uses points within the specified range loaded into the scene. The speed is relatively fast, but changes in the scene's data loading may affect the calculation result.
- Dividing Roof Layer (default off): When enabled, roof layers are clustered and roof boundaries are extracted for each height level within the selected area. When disabled, only the overall boundary is extracted.
- Min Area (square meters): The minimum area for the extraction region. Boundaries smaller than this area will be discarded.
- Inner (default off): Whether to extract internal boundaries. If enabled, the internal void boundaries of roofs with holes will be retained.
- Outer (default on): Whether to extract the outer boundary. If enabled, the outer boundary of the roof will be retained.
- Regularization (default on): Whether to regularize the extracted boundary. When enabled, the boundary is simplified and organized.
- Angle Tolerance (degrees): Effective when regularization is enabled. The angle threshold for regularization is typically set between 15°-30°. A larger value will reduce the number of sharp angles on the boundary.
Extract Building Footprint from Mesh
Activate the building contour extraction from model function
This function extracts building contours from the model. A parameter dialog box will pop up:
Min Area (square meters): The minimum area for the extraction region. Boundaries smaller than this area will be discarded.
Regularization (default on): Whether to regularize the extracted boundary. When enabled, the boundary is simplified and organized.
Angle Tolerance (degrees): Effective when regularization is enabled. The angle threshold for regularization is typically set between 15°-30°. A larger value will reduce the number of sharp angles on the boundary.
Click the left mouse button to confirm the level cutting plane position and execute contour extraction.
Trace Toe Tool
Refer to Toe Line Extraction Tool
Draw by Intersection
Activate the intersection line drawing method for vectorizing buildings
- Click the left mouse button to sequentially select two points on one edge of the building.
- Click the left mouse button to sequentially select two points on another edge of the building.
- The selected two edge lines will automatically extend to intersect at a point.
- (Optional) Right-click to bring up the context menu and choose to close the polyline, undo a point, or end the current operation.
- (Optional) Click the toolbar's undo button to undo a selected vertex.
- (Optional) Click the toolbar's close button to automatically close the current polyline and end the intersection line drawing.
Extract Feature by SAM
Activate the function to automatically extract vectors from images
Click on the image with the mouse to automatically recognize vectors from the image.
Parameter Settings
- Selection Tool: Specifies the interaction mode for automatic vector extraction.
- Point Selection: Left-click with the mouse to automatically extract the vector. Hold down the shift key while left-clicking to add a positive point. Hold down the alt key while left-clicking to add a negative point.
- Rectangle Selection: Left-click with the mouse to determine the starting point of the rectangle, move the mouse, and left-click to determine the endpoint of the rectangle. The vector will be automatically extracted.
- Simplification: Simplifies the extracted vector.
- Maximum Pixel Distance: Specifies the maximum distance deviation to retain points to the line. As the distance decreases, more points are retained, and fewer are deleted from the line.
- Smoothing: Smooths the extracted vector.
- Mean Smoothing (3\5\7 neighborhood): Uses the 3\5\7 neighborhood for mean smoothing for each point on the vector line.
- Bezier Smoothing (Line Control): Smooths using piecewise Bezier curves, generating a vector line that does not pass through control points.
- Bezier Smoothing (Point Control): Smooths using piecewise Bezier curves, generating a vector line that passes through control points.
- B-Spline Curve (Point Control): Smooths using cubic B-spline curves, generating a vector line that passes through some control points.
- B-Spline Curve Fitting: Fits using cubic B-spline curves, generating a vector line that does not pass through control points.
- Regularization: Regularizes the automatically extracted vector.
- Angle Threshold: Merges line segments with angles smaller than this threshold into a straight line.
- Maximum Pixel Distance: Specifies the maximum distance deviation to retain points to the line. As the distance decreases, more points are retained, and fewer are deleted from the line.
- Grounding: Adheres the automatically extracted vector to the point cloud or model, automatically modifying the elevation of the extracted vector line's nodes.
- Low Point: Uses the 3\5\7 neighborhood for mean smoothing for each point on the vector line.
- Mid Point: Smooths using piecewise Bezier curves, generating a vector line that does not pass through control points.
- High Point: Smooths using piecewise Bezier curves, generating a vector line that does not pass through control points.
- Output Result: Specifies the type of automatically extracted vector.
- Polygon: Specifies that the automatically extracted result is a polygon.
- Rectangle: Specifies that the automatically extracted result is a rectangle.