Vector Analysis

This tutorial shows how to add a vector layer to the map, style it, and run a GRASS vector module on it.

Prerequisites

• A GRASS environment with at least one vector map
• FastGIS connected and an environment selected

1. Add a vector layer

1. Click the △ (Add Vector) toolbar button
2. Select your vector map from the dropdown
3. Click Add to Map

The vector layer appears in the Layer Manager with a V badge.

2. Style the vector

1. Click the style button on the vector layer row in the Layer Manager
2. The inline style panel expands:
   • Pick a Color with the colour picker
   • Adjust Alpha (transparency) with the slider
   • Set Width for line/polygon stroke
3. Changes apply live to the Cesium viewer

3. Set the region to match the vector

1. Open the Computational Region panel (click □ in the toolbar)
2. Select your vector in the Match raster(s) list
3. Click Set region to raster(s)

(GRASS treats this as setting the region bounds to the vector's bounding box.)

4. Run a vector module

As an example, run v.buffer to create a buffer around the vector:

1. In Run Module type v.buffer and click Load ↓
2. Fill in:
   • input → your vector map
   • output → e.g. buffer_result
   • distance → buffer distance in map units
3. Click ▶ Run

5. Add the result to the map

Once the module finishes, click △ → select buffer_result → Add to Map.

Adjust the opacity and colour via the Layer Manager to overlay the buffer on the original vector.

6. Identify features

Click the ℹ (Identify) toolbar button, then click a location on the map. A popup shows the v.what result for any vector layers at that point.