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QGIS

QGIS is the most common upstream tool for prepping vector data before bringing it into Siter — coordinate-system transformations, format conversions, cleanup, and (when needed) vectorizing a scanned drawing into polylines that can be imported as a background layer. Siter does not import rasters as layers, so QGIS's role in this workflow is always upstream of a vector export.

This lesson covers the parts of QGIS that matter for prepping Siter data — not a full QGIS tutorial. For comprehensive QGIS documentation, consult the QGIS project's own materials.

Learning objectives

By the end of this lesson you should be able to:

  • Recognize when QGIS is the right tool for a prep task
  • Reproject vector data to a Siter-friendly CRS and export as GeoJSON
  • Recognize when a scanned drawing needs to be georeferenced and vectorized before it can become a Siter background layer

When to reach for QGIS​

QGIS earns its place in the Siter workflow for a few vector-prep tasks:

  • Coordinate system transformations — taking shapefiles in state plane (or any other projection) and reprojecting to WGS84 for clean GeoJSON export
  • Format conversion — turning AutoCAD .dwg into shapefile or GeoJSON via a more reliable conversion path than direct AutoCAD-to-Siter
  • Cleanup of imported AutoCAD or shapefile data — fix self-intersections, remove duplicate geometry, filter to relevant features
  • Spatial joins or filtering that you'd rather do in QGIS than in Siter
  • Vectorizing a scanned drawing — if the only source for a site plan is a raster scan, georeference it and trace the relevant features as polylines before bringing the vectors into Siter (Siter can't consume the raster directly)

The output of QGIS in every case is vector data — GeoJSON or shapefile — that Siter then imports as a background layer.

Exporting to GeoJSON for Siter​

Once your vector data is correctly positioned and in the right coordinate system in QGIS:

  1. Right-click the layer in the QGIS Layers panel and choose Export → Save Features As
  2. Set the format to GeoJSON
  3. Confirm the CRS is EPSG:4326 (WGS 84) — Siter expects this
  4. Save the file
  5. Import into Siter via the GeoJSON import flow

If the QGIS layer is not already in WGS84, the export step will reproject it on the fly. Verify in Siter after import that the geometry lands at the expected real-world location.

A common workflow​

The end-to-end QGIS-prep pattern for a typical site:

  1. Receive a shapefile in state plane coordinates from the installation's GIS department
  2. Open in QGIS
  3. Reproject to WGS84
  4. Clean up: filter to only relevant features, fix any obvious geometry issues
  5. Export as GeoJSON
  6. Import into Siter as a background layer
  7. In Siter: verify layer flavor, set type codes, fill in attributes via bulk editing

The QGIS leg of this is 10-15 minutes for a clean source, several hours for a messy one. Plan accordingly.

Vectorizing a scanned drawing (high level)​

If the only source you have is a scanned site plan, the path to a Siter background layer goes through QGIS in two phases:

  1. Georeference the raster — use the QGIS Georeferencer plugin to assign real-world coordinates to the scan via control points (building corners, intersections, survey monuments). The QGIS docs cover this in detail.
  2. Vectorize the relevant features — trace the building footprints, road centerlines, parcel boundaries, etc., as polyline or polygon vector layers in QGIS. This is the step that produces something Siter can import.
  3. Export the vector layers as GeoJSON and import as a background layer in Siter.

The georeferenced raster itself is not what Siter consumes — only the traced vectors are. If you skip the vectorization step, you have nothing to import.

[TODO: FILL IN — pointers to QGIS documentation for the Georeferencer plugin and the digitizing tools used for vectorization.]

What this lesson is not​

This is not a QGIS tutorial. The intent is to orient you to where QGIS sits in the Siter workflow, not to teach QGIS itself. For deeper QGIS knowledge, consult:

  • The official QGIS documentation
  • A dedicated QGIS course or book