16 slides
Lecture · 15 minutes
Silent Success
QGIS said it worked. The map stayed empty. Learn the check that catches it.
25-minute build · 5-minute questionsQGIS 4.2 · works offline
Where Heat Meets People.
In 25 minutes, open London heat data, catch a silent styling error, find one defensible insight and export a checked PDF in QGIS 4.2.
Can you trust a map that QGIS says loaded?
View the lecture and workshop slides
London worked example
Catch an empty style, repair it, then publish one checked map.
Get ready
Three steps before we start.
The workshop runs from one offline pack. You need no account, API key, plug-in or internet connection.
- 01Download QGIS
Install QGIS 4.2.0
Open Help, then About, and confirm the version once.
- 02Download pack
Download and unzip the pack
Keep every folder together. The pack includes six recovery projects.
- 03Open guide
Open 00_open.qgz
Keep the two-page guide beside QGIS and wait for the first check.
The 25-minute build
Five stages. One visible result each.
Each stage ends with something you can see or count. If a check fails, open the supplied recovery project and carry on from there.
- 0100:00 to 02:30
Learn the map
Name the geometry, attributes and coordinate reference system.
You can explain what one QGIS layer contains.
- 0202:30 to 06:30
Check the data
Open the GeoParquet and confirm 16,659 polygons plus the expected heat column.
The file is loaded and its structure is proved.
- 0306:30 to 12:00
Catch and fix the error
Apply the broken style, stop at zero coloured cells, then use the corrected field.
The same layer changes from 0 to 16,659 classified cells.
- 0412:00 to 16:30
Find one insight
Select the upper map class and count it before interpreting it.
105 cells, 0.63%, with the limits stated beside the result.
- 0516:30 to 25:00
Design and export
Set the reading order, export the PDF and reopen it outside QGIS.
One checked map with a visible legend, scale and sources.
The clearest example
One wrong column name makes a valid map look empty.
Before · 0 coloured cells
The style requests exposure_pdc. That column does not exist.
After · 16,659 coloured cells
The corrected style uses heat_exposure_pk_per_km2.
Design with intent
Make the map easy to read.
- 01
Hierarchy
The claim and map speak first. The legend and scale support them.
- 02
Restraint
One heat ramp, thin context lines, generous space and a quiet north arrow.
- 03
Evidence
The observation, its boundary and its sources stay on the page.
The slides
Choose a deck.
The 15-minute lecture explains the failure. The 25-minute workshop guides the fix.
12 slides
Workshop · 25 + 5 minutes
Where Heat Meets People
Follow the London build from first layer to reopened PDF.
Browser and offline QGIS versions include participant evidence and sources. Presenter notes remain private.
Take it with you
Three useful links.
Continue after the workshop
Keep the checking rule. Change the city.
Write a plan for your own city in your browser, keeping the same five checks.