Participant start · page 1 of 2

Can you trust this map?

Where Heat Meets People

A 30-minute QGIS evidence-to-publication challenge. Arrive with QGIS 4.2 and the public rehearsal pack. In the room, follow one observable end state at a time and stop the build at 25:00.

Proposed date: 12 August 2026, organiser confirmation pending Proposed venue: Birkbeck, Malet Street, London WC1E 7HX Target: QGIS 4.2.0, Belém do Pará Working time: 25 minutes plus 5 minutes for questions
Readiness warning: this is a technical rehearsal candidate. The archive passed automated QGIS 4.2 relocation, replay and export checks. The human room rehearsal and a second physical-machine check remain. Use it to practise now, but do not describe it as the final event pack.

Download and prepare

  1. Install QGIS 4.2.0 for your operating system, open it once and confirm the version under Help, About.
    Official Windows, macOS and Linux options. Checked 5 August 2026.
  2. Download the single QGIS 4.2 participant ZIP, then compare its published SHA-256 with materials.json.
  3. Extract the complete ZIP. Keep its folders together and open 00_open.qgz.
  4. Optional inspection copies: GeoParquet, broken QML and repaired QML. The participant ZIP already contains them.

Before arrival

  1. Install and open QGIS 4.2.0 once.
  2. Download and unzip the complete rehearsal pack into one readable folder.
  3. Confirm 00_open.qgz opens, then leave it with no GeoParquet layer loaded.
  4. Do not load the data or either style before the workshop. Those are timed actions 01 to 05.
  5. Bring your laptop and charger. If the file does not open, plan to pair with a prepared machine.

What to do in the room

  1. Wait for the facilitator to confirm whether the rehearsal candidate or final event pack is in use.
  2. Before 00:00, open 00_open.qgz, keep every supplied file together and confirm no GeoParquet layer is loaded.
  3. Start the 25-minute build clock only when the whole room is at that same empty project state.
  4. Follow the numbered actions on page 2. Do not install a driver, plug-in or Python package.
  5. You need no account, API key or MCP server for the participant flow.

The 30-second recovery rule

If you are more than 30 seconds behind at a checkpoint, open the named state below. When QGIS asks, discard unsaved changes. The recovery state is authoritative; do not debug while the room waits.

CheckpointOpen
05:0001_loaded.qgz
10:0002_broken.qgz
12:0003_fixed.qgz
16:3004_insight.qgz
19:3005_export_ready.qgz
22:30Checked reference PDF

Public references

Proof card and paper exit ticket · checked reference PDF · offline web-map reference, not produced in the timed build · browser workshop slides · checksums and provenance

This guide renders without external fonts, scripts, images or styles. The links above retrieve separately published files when a network connection is available.

To print: choose A4 portrait, 100% scale, background graphics on, and browser headers and footers off.

geospatial.careers/workshops/qgis4-london-heat

Participant guide v1 · CC BY 4.0

The proof loop · page 2 of 2

Nine phases, five checks

The software reporting success is not the outcome. Continue only when the relevant end-state check is observable.

The exact five proof checks

LoadDeclared GeoParquet, EPSG:4326, exactly 16,659 features.
Schemaheat_exposure_pk_per_km2 exists and has values.
StyleThe renderer uses that field and its classes contain features.
AnalysisThe frozen expression selects exactly 105 cells.
ExportThe PDF exists, is non-empty and visibly contains the map furniture.
Source
h3_heat_exposure_r9.parquet
Features
16,659
Source CRS
EPSG:4326 / OGC:CRS84
Project CRS
EPSG:27700
Style
7 classes, 16,659 classified
Expression
"heat_exposure_pk_per_km2" >= 40000
Selection
105 cells, 0.63%
Snapshot
29 July 2026, daytime
  1. 00
    Foundation · 00:00 to 02:30

    Name geometry, attributes and coordinate systems.

    Points locate, lines trace, polygons enclose and rasters sample. Today the layer uses H3 polygons.

  2. 01
    Open · 02:30 to 05:00

    Open the H3 GeoParquet.

    Use the declared file. Confirm the layer is spatial and the source remains unchanged.

  3. 02
    Prove · 05:00 to 06:30

    Prove the expected feature count and required field.

    Continue only with 16,659 features, EPSG:4326 and the exact exposure field.

  4. 03
    Break · 06:30 to 08:15

    Apply the intentionally broken style.

    Load heat-exposure-broken.qml. It points to exposure_pdc, a missing field.

  5. 04
    Stop · 08:15 to 10:00

    Stop when the proof gate detects that no feature is classified.

    The blank map is an expected rejected state. Do not treat a loaded style as proof.

  6. 05
    Repair · 10:00 to 12:00

    Repair the field contract and prove the rendered result.

    Load heat-exposure-fixed.qml. All 16,659 cells must land in its seven fixed classes.

  7. 06
    Interrogate · 12:00 to 16:30

    Record one bounded London heat observation with its caveats.

    Select exactly 105 cells. The 40,000 boundary is cartographic, not a health threshold.

  8. 07
    Design and export · 16:30 to 22:30

    Export the proved map and reopen the PDF.

    Inspect the title, map, legend, scale bar, observation, conditions and attribution.

  9. 08
    Transfer · 22:30 to 25:00

    Leave with the city-remix prompt and reusable checking rule.

    Change the place and input, but keep an observable proof before every continuation.

At 25:00, stop building and keep the city-remix slide visible. Use 25:00 to 30:00 only for questions. Complete the optional paper ticket after 30:00. If you fall behind, use the checkpoint table on page 1; open the checked reference PDF at 22:30 if export remains unproved.

Troubleshooting

  • Wrong QGIS version: pair with a tested QGIS 4.2 machine.
  • GeoParquet will not open: confirm the exact file, then pair with the prepared machine or use the checked reference PDF.
  • Blank after the broken style: expected. Name the missing field and continue.
  • Blank after repair: reload heat-exposure-fixed.qml. If it remains blank, use the checked reference PDF and continue.
  • Selection is not 105: use Replace current selection and paste the exact expression.
  • PDF fails: open the checked reference PDF and inspect the required map furniture.
  • More than 30 seconds behind: use the checkpoint table on page 1 and open its named recovery state. Use the reference PDF at 22:30 if export is still unproved.

Hands off at 25:00

  1. Stop building. Keep the city-remix slide and your finished output visible through questions.
  2. Use 25:00 to 30:00 only for questions; do not borrow it to finish the map.
  3. After 30:00, keep the released folder and PDF together and complete the optional paper exit ticket.
  4. Name one end-state check and one future city as place, input and proof.

Land surface temperature is not air temperature, thermal comfort or individual heat risk. The snapshot uses one daytime scene, modelled population and an author-chosen H3 resolution 9 support.