# Slopes

## Concepts

Slope extension calculates slopes along given line segments based on the height information derived from a point cloud. The slope value is the height difference of the endpoints divided by the horizontal segment length (Slope WIKI). The measure unit used for the segment is percentage, so a 45 degree angle has slope 100.

The segments can be provided directly as line vector features (each line can only have 2 vertexes: beginning and end points) or they can be calculated from given area rectangular features. Segment perpendicular to an existing one can also be derived.

The line segments are used to define vertical slices and the linear regression is used to find the slope line. Linear regression approach allows to obtain reliable, noise-proof results ( Linear Regression WIKI). From the point cloud the biggest cluster by time is used in the calculations to ensure best relative accuracy of the points and avoid errors related to misalignment related to double passes.

## Sidebar

### Project

**Select point cloud dataset drop-down menu**

Choose one of the available in the Dataset List *.opc point cloud files to use in slope calculations.

**Project**

Choose where you want to store the Slope extension results. A project represents an automatically created destination in the same folder where the source point cloud is stored.

For each run of Slope extension a new project will be created. Writing new data in an existing project will overwrite existing data in that folder.

Options to create a new project, open a recent project, close or delete a project are available.

### Input

Select the input type: line segments or area rectangles.

If the rectangles are provided the slopes will be calculated along line segment going through the centroid of the rectangular and parallel to the the longest side of it.

**Choose input drop-down menu**

Choose one of the available in the Dataset List vector files to use in slope calculations.

### Options

**Slice Thickness** and **Slice Length**

Extensions of the slice in meters.

**Z Range**

The maximum Z in meter of the points above the lowest Z value in the slice.

**Min Points**

Minimum amount of points needed in the slice for the slope line to be calculated.

**Create Cross**

If enabled then the cross section (perpendicular line segment through the center of the original one) will be created for each given segment and the slope along it will be calculated. The cross section is of equal length to the original line segment, and runs from left to right when looking along the original line segment.

### Process

**Intermediate Files**

Enables keeping all intermediate files.

Keeping intermediate files allows to make deeper analysis of the results (they allow to visualize the calculated best fitted line and all slice points projected to a vertical plane). Following files will be additionally created for every XXX input feature:

- calculate_slopes_slice_points_XXX.ovf
- calculate_slopes_line_points_XXX.ovf
- calculate_slopes_slope_points_XXX.ovf
- calculate_slopes_slope_errors_XXX.txt

**Delegate to Task Manager**

Allows to schedule job to be run later by delegating it to the Task Manager.

**Start Now**

Start calculating of the slopes immediately.

### Export

**Export the Theme**

Creates Asset Inventory Theme which can be used for result's verification for example.