DEV Community: Raymond Lay

Seamlessly Compare Maps on QGIS with the QMapCompare Plugin

Raymond Lay — Sat, 22 Feb 2025 02:10:46 +0000

Introduction

When working with QGIS, you often switch between basemaps, but comparing small differences between maps can be challenging when only one map can be displayed at a time.

Web tools like Japan's "Past/Present Map on the Web" and France Mapping Agency (IGN)'s "Remonter le temps" enable users to compare different styles of maps easily in various ways.

However, QGIS has lacked a stable feature for map comparison until now! This post introduces QMapCompare, a new plugin that enables users to compare multiple maps directly within QGIS using various visualization methods.

QMapCompare overview. Created by editing GSI Tiles

Installation

First, ensure you are using QGIS version 3.34 or later.
Then, you can install plugin by searching QMapCompare on QGIS plugin manager.

Usage

Once plugin installed, a new icon will appear on the toolbar.
Clicking the icon will toggle the QMapCompare panel on the left bottom of QGIS window.

QMapCompare interface. ©︎OpenStreetMap contributors

QMapCompare provides several ways to compare maps.

Select layers you want to compare (1), and choose the following comparison method (2-5):

1. Select compare layers (multiple selections allowed)
2. Mirror: Displays two maps side by side
3. Vertical Split: Divides the map vertically
4. Horizontal Split: Divides the map horizontally
5. Lens: Check compare layers with a circle around the mouse cursor
6. Stop: Ends the comparison

Comparison Methods Overview

Mirror View

The mirror mode places a duplicate of the map canvas on the right side of the map canvas.

This is useful when comparing base maps with satellite imagery or other data.

Mirror view. Created by editing GSI Tiles

Split View

The split mode divides the map into two sections, showing different layers side by side.

You can choose either a vertical or horizontal split, depending on your needs.

This is may be useful for comparing building accuracy in OpenStreetMap with government-provided data as example.

Split view. Created by editing GSI Tiles and ©︎OpenStreetMap contributors

Lens View

Lens mode displays a circular preview of the comparison layers around the mouse cursor.

As you move the cursor, the preview updates in real time.

This is especially useful for detailed comparisons of specific locations.

Lens view. Created by editing GSI Tiles

Practical Use Cases

QMapCompare is valuable for various use cases as below:

Comparing historical aerial photographs

Tokyo Aerial Photo Comparison between 2024(left) and 1987-1990(right).
Created by editing GSI Tiles

Analyzing pre- and post-disaster images

Aerial Photo Comparison of Before 2021 Atami Landslip Disaster (left) and after(right).
Created by editing GSI Tiles

Conclusion

QMapCompare is a powerful tool for comparing different maps and datasets within QGIS. With this plugin, you can easily:

Analyze time-series data (e.g., pre- and post-disaster maps)
Evaluate data accuracy (e.g., comparing OpenStreetMap with government maps)
Support decision-making (e.g., verifying different analytical results and styles)

As this is a newly released plugin, there may still be some bugs. If you encounter any issues, please report them on our GitHub Issues page.

Your feedback will help improve the tool!

Retrieve satellite earth observation images easily with QGIS JAXA Earth API Plugin

Raymond Lay — Wed, 26 Jun 2024 05:52:58 +0000

Abstract

Climate is changing rapidly, and these changes must be monitored continuously, especially with satellite observations.

The Japan Aerospace Exploration Agency (JAXA) publishes Earth observation images, such as temperature, precipitation amount, vegetation, etc., which can be retrieved using the JAXA Earth API.

This post describes how to retrieve georeferenced observation images using the JAXA Earth API plugin for QGIS.

JAXA Earth API overview

JAXA Earth API is a satellite data distribution service, written in Python and javascript.
Description and available dataset are detailed in the official website : https://data.earth.jaxa.jp/

Observation images can be retrieved easily, but it would be better to overlay onto a basemap, that is why the use of a Geographic Information System (GIS) such as QGIS may be useful.

The use of QGIS JAXA Earth API Plugin

QGIS is an Opensource GIS software, and we can gather and analyse geographic data easily.
QGIS is also customizable using python scripts or adding plugins on.
Here is a procedure to install QGIS JAXA Earth API Plugin and retrieve satellite data.

1. On QGIS and add OpenStreetMap basemap

Open QGIS

Basemap should be used as background to show map context.
It can be added on QGIS as XYZ tile.

On browser, right click on XYZ tiles
New connection…
Put a name to this connection and input https://tile.openstreetmap.org/{z}/{x}/{y}.png link as URL
OK

OpenStreetMap should be displayed on map canvas.

2. Install JAXA Earth API Plugin

Menu -> Plugins -> Manage plugins...

On plugin manager, search for JAXA and install

Once plugin installed, JAXA Earth API icon should appear on tool bar

By clicking on plugin icon, plugin dialog should appear

3. Plugin use example

1. Choose target dataset (here precipitation rate monthly)
2. Choose target period
3. Choose target map extent
- By clicking on Map Canvas Extent button, map current is set
- Custom extent can also be set by clicking on Draw on Canvas button
4. Push Launch button to load data

Dataset is loaded as one layer per month!

At last

Regarding results, precipitation rate evolution can be checked monthly.
Animation of this evolution can be made using TimeManager plugin
If you see any bug or have an enhancement idea, feel free to put an issue here :
https://github.com/MIERUNE/qgis-jaxa-earth-plugin

Get started with PyQGIS 03 - Manipulate vector layers with QGIS python console

Raymond Lay — Wed, 31 Jan 2024 10:17:52 +0000

On the previous chapter, we get started with vector layer classes called QgsVectorLayer.

It could be set as follow:



file_path = "your/path/data/target_file.shp"
layer_name = "my fantastic layer"

# declare a new layer and specify file_path and layer name
layer = QgsVectorLayer(file_path, layer_name, "ogr")
# import declared layer 
QgsProject.instance().addMapLayer(layer)

and layer name can be retrieved as follow :



# each layer is a QgsVectorLayer object
for layer in QgsProject.instance().mapLayers().values():
     print(layer.name())

Regarding documentation, QgsVectorLayer class is full of functions. Let check some basic functions with QGIS python console!

1. Open script editor of Python Console

In Python console we can launch commands one by one, but we need several commands to manage layers.
To run those at once, we need to open the script editor.

1.1. Open Python console in QGIS

As for the first chapter :
Open QGIS, menu -> Plugins -> Python Console

Or use shortcut Ctrl+Alt+P (Windows) command+option+P (mac)

Python console open usually at the bottom of QGIS frame

1.2. Open Script Editor

Click on the Show Editor button to open script editor as below:

2. Vector Layer related commands

Import the vector layer you want, here is Japan Prefectures

2.1. Retrieve target layer by name

As last chapter, we will retrieve layer by name (here japan_pref ), by



layer = QgsProject.instance().mapLayersByName("japan_pref")[0]

# check
print(layer)

Result :



<QgsVectorLayer: 'japan_pref' (ogr)>

2.2. Retrieve layer extent

Simply add



layer_extent = layer.extent()
print("extent: ", layer_extent)

The result should be a QgsRectangle object.



extent: <QgsRectangle: 122.93372516199046629 24.04561582899132333, 148.89439264601270452 45.55724341400912891>

Coordinates looks to be in geographic system, let's check.

2.3. Retrieve layer extent

Simply write



layer_crs = layer.sourceCrs()
print("CRS: ", layer_crs)

The result should be the WGS 84 (EPSG:4326) reference system.



CRS: <QgsCoordinateReferenceSystem: EPSG:4326>

2.4. Retrieve the number of features of the target layer

featureCount() method can do it.
you can combine with name() method to write a clean message



msg = f"{layer.name()} layer has {layer.featureCount()} features."
print(msg)

And here is the number of Japan prefectures:



japan_pref layer has 47 features.

2.5. Retrieves vector layer fields

You can try



layer_fields = layer.fields()
print (layer_fields)

Result is an unreadable code, BUT!
class name QgsFields makes us to find a way to solve it.



<qgis._core.QgsFields object at 0x0000024950231160>

Let's check documentation.
You can check by searching QgsFields with your favourite search engine.
Regarding, Qgs Fields Documentation names method may be fine.

Let's try!



layer_fields = layer.fields()
print (layer_fields.names())

I got it !

3. Check output PyQgis class and its methods, a good pratice to make you grow up in PyQGIS

In this chapter, QgsVectorLayer basic methods has been used, and regarding documentation, many other usages can be done.

The last method to retrieve field is a combination of QgsVectorLayer and QgsFields.
However, we saw that when we hit to an unknown class, we can still moving on by checking documentation of this class, and find the good method easily.

This is a good way to understand easily a huge library such as PyQGIS.

Solving QGIS plugin conflict

Raymond Lay — Thu, 02 Nov 2023 04:19:30 +0000

QGIS is full of useful plugins which enlarges scope of location data analysis.

However, sometimes plugin install does not work due to the following error :

Plugin 'qgis-plugx-plugin' could not be loaded due to an error calling its classFactory() method

ImportError: cannot import name 'write_json' from 'utils' (/Users/xxxxxx/Library/Application Support/QGIS/QGIS3/profiles/default/python/plugins/qgis2web/utils.py)

This error occured when trying to install qgis-plugx-plugin but error refers to another plugin called qgis2web in this example.

Source : https://github.com/MIERUNE/qgis-plugx-plugin/issues/160

This short article show 2 ways to solve this conflict.

Way 1 : Turn off one of contentious plugins

In plugin manager, turn off one of the plugins source of conflict.

Then relaunch QGIS.
To use the other one, check/uncheck contentious plugins again and relaunch plugin.

This is not really a solution, but to solve it sustainably, you can ask plugin developer(s) by throwing an issue on plugin repository.
You can usually access to bug tracker through QGIS plugin manager,

Way 2 : avoid using utils.py (for plugin developers)

Above error message shows that utils module seems to be source of conflicts.

[...]
ImportError: cannot import name 'write_json' from 'utils' [...]

utils.py files from various plugins looks to be compiled in QGIS core system, and having the same module name may be source of conflict.
If you are developer of the issuing plugin, a way to solve this problem is simply to rename such a global name in root folder e.g: utils.py to yourpluginname_utils.py.

Example:

Then, peace is back between plugins!

Get started with PyQGIS 02 - Manage layers with QGIS python console

Raymond Lay — Wed, 25 Oct 2023 12:08:54 +0000

The first chapter of this PyQGIS tutorial series told about basic commands and approach of PyQGIS module.
This second chapter tell you about how to manage layers with some usual commands.
You can use your own data or use a sample data of Paris region cities from France government platform.

1. Open script editor of Python Console

In Python console we can launch commands one by one, but we need several commands to manage layers.
To run those at once, we need to open the script editor.

1.1. Open Python console in QGIS

As for the first chapter :
Open QGIS, menu -> Plugins -> Python Console

Or use shortcut Ctrl+Alt+P (Windows) command+option+P (mac)

Python console open usually at the bottom of QGIS frame

1.2. Open Script Editor

Click on the Show Editor button to open script editor as below:

2. Layer related commands

Here are some basic commands to manage layers in a QGIS project.

2.1. Import layer from file

Layer can be load in QGIS with two commands:



# 1- declare a new layer and specify file_path and layer name
layer = QgsVectorLayer(file_path, layer_name, "ogr")
# 2- import declared layer 
QgsProject.instance().addMapLayer(layer)

On script editor, copy the following code, adapt to the file you want to import, and run.



file_path = "your/path/data/target_file.shp"
layer_name = "my fantastic layer"

# declare a new layer and specify file_path and layer name
layer = QgsVectorLayer(file_path, layer_name, "ogr")
# import declared layer 
QgsProject.instance().addMapLayer(layer)

2.2. Import only a part of features from file

We can import a part of features by filtering declared layer.
The following command will filter data where
target_field = 'target_value'
and it should be put before import command.



layer.setSubsetString("target_field='target_value'")

In process, layer name will be added with 'filtered' suffix:



file_path = "your/path/data/target_file.shp"
layer_name = "my fantastic layer filtered"

# declare a new layer and specify file_path and layer name
layer = QgsVectorLayer(file_path, layer_name, "ogr")
# filter layer before import
layer.setSubsetString("target_field='target_value'")
# import declared layer 
QgsProject.instance().addMapLayer(layer)

On below pic, data is filtered with only Paris' wards with:



layer.setSubsetString("numdep=75")

2.3. List layers

There are various ways to list layers: we can retrieve layers as object or just layers name.

Running following command directly on python console will show a list of layer, not by layer name, but by object showing layer ID, and their PyQgis type: ```python

QgsProject.instance().mapLayers()


![map layers](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/58txmk5l8uexwp1jnoip.png)

- Adding `.values` on above result will reduce response to class and layer name:
```python


QgsProject.instance().mapLayers().values()

To retrieve only layers' name, use the .name() attribute of each layer object:



for layer in QgsProject.instance().mapLayers().values():
     print(layer.name())

2.3. Retrieve a layer by name

A layer can be retrieved by name with the following command:



QgsProject.instance().mapLayersByName("search_layer_name")

This is the main way to retrieve a layer and manipulate it.
This command will not return layer, but a list of layers which fit to target name.

So, to get layer as unique, you can add an iteration like [0], which means the first matching of returned list:



QgsProject.instance().mapLayersByName("search_layer_name")[0]

2.4. Remove layer

removeLayer method of QgsProject.instance() is used.
As written in documentation, target layer ID is required.

layer ID can be retrieved with by adding .id() method of layer class that we retrieved in previous step.



layer = QgsProject.instance().mapLayersByName("search_layer_name")[0]
print(layer.id())

Thus, we can use this id to remove layer.



layer = QgsProject.instance().mapLayersByName("search_layer_name")[0]
QgsProject.instance().removeMapLayer(layer.id())

3. The use of QgsProject class to manage layers

In this second chapter, QgsProject.instance() has been mainly used to add, retrieve and remove layer.
Regarding documentation, many other manipulations can be done, such as remove all layers or manipulate other project matters.

Retrieving layers as objects also makes introduced us to QgsVectorLayer which will be the topic of the next chapter.

Get started with PyQGIS 01 - Some basic commands with QGIS python console

Raymond Lay — Wed, 13 Sep 2023 13:43:03 +0000

QGIS is a useful GIS opensource software which offers many ways of views and analyze geospatial data.
However analysis tools and basic functionalities may be not enough for specific needs, or when tasks need to be automated or easier to use.

PyQGIS is an API which allows us to code in python in QGIS and manipulate many functionalities.
This library is however so wide that it is difficult to know how to get started.

This post is a first step to get started with PyQGIS, from very basic commands.

1. Open Python console in QGIS

Open QGIS, menu -> Plugins -> Python Console

Or use shortcut Ctrl+Alt+P (Windows) command+option+P (mac)

Python console open usually at the bottom of QGIS frame

2. Run first commands

2.1. Hello world command

Use print("some_result") to display a result



print("hello_world")

"hello_world"

Command

result

2.2. Get map canvas scale

By launching the following command on python console, Current scale of map canvas can be retrieved.



iface.mapCanvas().scale()

2.3. Set map canvas scale

With the following command launched on python console, map canvas can be set to 1:25,000 scale



iface.mapCanvas().zoomScale(25000)

3. Understand commands and PyQGIS library



iface.mapCanvas().scale()
iface.mapCanvas().zoomScale(25000)

Above commands looks not intuitive at a first view, but Python console of QGIS allows us to investigate commands components easily.

For example if we inquiry only



iface.mapCanvas()

Console will return



<qgis._gui.QgsMapCanvas object at 0x1ac03ab80>

which means that iface.mapCanvas() is a QgsMapCanvas object of PyQGIS.

By searching QgsMapCanvas pyqgis on your favorite search browser, you'll get documentation of this class,
https://qgis.org/pyqgis/3.2/gui/Map/QgsMapCanvas.html
and have access of all methods that iface.mapCanvas() is able to do.

Thus, you can try many of methods of QgsMapCanvas class.
Here are two examples:

3.1. center to retrieve center point of map canvas



iface.mapCanvas().center()
<QgsPointXY: POINT(454338.46291687525808811 5845991.44166376255452633)>

3.2. extent where canvas extent can be retrieved



iface.mapCanvas().extent()
<QgsRectangle: 452382.75110932614188641 5845268.24721858091652393, 456294.17472442437428981 5846714.63610894419252872>

etc.

4. First conclusion of PyQGIS approach

Python console of QGIS is very useful to understand PyQGIS.
By launching first commands, and inquiry commands prefixes such as iface.mapCanvas(), you can discover a PyQGIS class (here QgsMapCanvas) and the wealth of methods it offers.

PyQGIS is a very wide library, and understand its architecture becomes easier by inquiring a class like above on the Python Console of QGIS, and discover methods on documentation.

Next post will focus on dealing with layers with pyQGIS

Remark:

in iface.mapCanvas(), you surely wondered what iface means. By the same approach we used on this post, you can run iface command, it will return the QgisInterface class and many many related methods.



# iface() with ()does not work
iface
<qgis._gui.QgisInterface object at 0x15589fe50>

Get started with QField cloud

Raymond Lay — Wed, 26 Jul 2023 12:39:30 +0000

Web and Desktop Opensource Geographic Information System (GIS) softwares are growing fastly and offers many analysis solutions.
However, on-field data acquisition solutions should also take into account.
Let's try one of those solutions called QField.

What's QField?

QField is an OS/Android/Windows GIS app where we can process field work.
Concretly, geospatial data can be digitalized, edited and well managed.

https://qfield.org/

And QField cloud?

Qfield projects can be cloudly stored like Google Drive.
It allows to be synchronized, be accessed by multi devices and/or users, and also to work on-field even offline.

https://qfield.cloud/

QField sync to manage field projects

QField sync is a QGIS plugin that allows to manage plugin projects on QGIS.
This is the strongest point of QField because it opens field data to whole GIS great functionalities.

https://plugins.qgis.org/plugins/qfieldsync/

To summarize QField work architecture

This architecture allows to work from QGIS and QField application by a syncronization logic like GitHub.

1. Setup

Many steps have to be done to create an operational QField project.
You can follow detailed steps from QField website, but it may be good to also have a look in below summary to understand easier how it works.

1- On Web browser:

If you don't have a QFieldCloud account, sign up
Login to your account and create a project

2- On QGIS:

install QFieldSync plugin
login to your QFieldCloud account
retrieve project created in QField cloud and synchronize
add data, configure and design it
synchronize (Push to cloud)

3- On field device (smartphone, tablet etc.)

install QField application
login to your QFieldCloud account
retrieve project created in QField cloud and synchronize
start your field work!

2. Use case: Locate vending machines with QField

Japan is full of drink vending machines, but density becomes low when going to countrysides.
Bad experiences occured when running long distance in summer, or when simply want to have a coffee break with no store and café around.

Project idea is to gather location of vending machines (and also toilets and stores) to be a good companion for runners, hikers and cyclists.

Here is how I getted started step by steps.

Prepare project layers on QGIS and push to cloud

Layers :

vending_machine
toilet

Push to cloud:
clic on synchronize

check and perform actions

Survey with QField

Let's run on the road and add feature when find a vending machine.

On QField, retrieve target project.
Turn in editing mode

Target point can be fit to current position, and feature is added with following buttons

Populate attributes and save

Once finished, edited features (here 5) can be push to the cloud as shown

Choose push only or synchronize

Get surveyed data on QGIS

On QGIS, clic on synchronize button :

Be Careful to the stream way!
I synchronization frame, upload is displayed, but in that case we need to download surveyed features from cloud.
Click on Prefer Cloud before Perform Actions .
Action list should be turned on Download

Well done!

Only 4 refresh spots and 5 vending machines were found after run 4 kilometers by 35°C...

3. Issues encountered

This section to summarize issues encountered and its solution if any.
It may be a technical issue or something I missed when setting parameters.
To be updated as far as I use.
Any suggestion is welcomed.

[enhancement] detect appropriate upload/download way

as written above

Dropping feature on QField device may not be detected when synchronizing in QGIS

Context

Point layer named store has been added.
1 feature has been added on QGIS at the same place of toilet

Feature has then been dropped in QField...

...but editing cannot be detected on QGIS side.

My first #30DayMapChallenge

Raymond Lay — Wed, 28 Dec 2022 13:17:07 +0000

2022 year is the first time I tried #30DayMapChallenge, a daily map making challenge which is held on Social Network every year in november.
I get known about it after the end of 2021 challenge and as a map lover, I did my best to not miss 2022 one.

30+6 maps completed

Map making has been started once topics were published few weeks before, knowing doing maps the same day for one month is so hard with work and family matters.

As a first step, most of output has been done as simple and/or in a very short time according to a famous sentence "Done is better than perfect", and some of topics has been selected to take more time on.

30 maps has been done in early november, so remaining time has been used to improve it, and make additional stuffs for MIERUNE (a GIS solution company in Japan) who also did the challenge as a team.

Below is a summary of made maps with used tools

Day	Topic	Output	Tool
1	Points	A Webmap with my posts on Facebook	Maptiler / Maplibre
2	Lines	Mt-Fuji contour lines	QGIS + ElevationTile4JP Plugin
3	Polygons	An upside down border between Belgium and Netherlands	QGIS
4	Colour Friday: Green	Greenland	QGIS
5	Ukraine	An ukrainian color globe map	QGIS + Globe Builder plugin
6	Network	Tokyo railway network comes to Paris	QGIS / Maptiler
7	Raster	Spatiomap of Mongolia	QGIS / Maptiler
8	Data: OpenStreetMap	Mashiko living town map with IGN French style	QGIS + ElevationTile4JP Plugin
9	Space	Patagonia Star Map	Photoshop & Your sky
10	A bad map	Mercator & Default Color	QGIS
11	Colour Friday: Red	Japan cities with「赤」Red Kanji	QGIS
12	Scale	Europa and Middle East cities longitudely translated to Japan	QGIS / Maptiler
13	5 minute map	Tokyo Marathon with 5 minutes checkpoint	QGIS / Maptiler
14	Hexagons	France, as known as L'Hexagone	Photoshop
15	Food/drink	The egg projection	Egg and Marker
16	Minimal	The minimal sized country	QGIS
17	A map without a computer	A clay of Antarctica	Clay
18	Colour Friday: Blue	Japan cities with「青」Blue Kanji	QGIS
19	Globe	A craft and paint made Globe	Watercolor
20	“My favourite…”	A lovely south pole	QGIS
21	Data: Kontur Population Dataset	Around Korea DMZ	QGIS
22	NULL	A globe clay waiting for data	Clay
23	Movement	Bus traffic around Mt. Fuji	QGIS + GTFS-GO plugin / Maptiler
24	Fantasy	Final Fantasy I~X worlds, 10 in 1	Photoshop
25	Colour Friday: 2 colours	Japan cities with「緑」green and 「紫」purple kanji	QGIS
26	Island(s)	Lovely Amami island	QGIS + ElevationTile4JP Plugin
27	Music	Where Songs I listened to come from?	QGIS
28	3D	One month of the run and trekking	Strava / QGIS + ElevationTile4JP + Qgis2threejs Plugin
29	“Out of my comfort zone”	Girondins de Bordeaux football teams opponents	Maptiler / Maplibre
30	Remix	A Webmap with my posts on Facebook, in Globe version	Mapbox

Additional Maps for MIERUNE

Day	Topic	Output	Tool
5	Ukraine	Hokkaido map in Ukrainian	Maptiler
12	Scale	Paris region railway network come to Tokyo	QGIS / Maptiler
13	5 minute map	A 5 minutes run with a 5 shape	Strava / QGIS / Maptiler
22	NULL	Hokkaido clay waiting for data	Clay
29	“Out of my comfort zone”	A Japan map made with business cards	Business cards
30	Remix	Greater Tokyo Railway Network come to Greater Paris	QGIS / Maptiler

Making maps with open tools

Regarding above summary, all maps has been made using open tools except Photoshop. Geographic tools are fully Open source.

Tool	Output count	Type
QGIS	23	GIS
Maptiler	11	Basemap Style
Maplibre	2	Webmapping
Mapbox	1	Webmapping
Photoshop	3	non-GIS use
Yoursky	1	Sky map
Strava	3	Running app
Clay	3	Non-digital use
Egg	1	Non-digital use
Watercolour	1	Non-digital use
Business card	1	Non-digital use

　* Total is over than 36 due to the use of multi-tools for some maps

A great opportunity to do unusual maps

Making maps is usually for work or customer needs, but this challenge makes me try to map random thoughts, such as where is Japan latitude equivalent in Europe, or How Tokyo is big comparing to Paris

A great opportunity to try new tools

Challenge was a chance to try new tools I never had any opportunity to try before.
Below is a list of what I learned during this month:

Mapping in 3D with QGIS (with Qgis2threejs plugin)
Mapping a Globe with QGIS (with Globe builder plugin)
Making a globe Webmap
Getting Japan elevation data easily (with ElevationTile4JP)
Making a starmap
Making a map and a globe with clay
Mapping with cards

Conclusion

More than 8000 maps has been released in one month.
Time was so short I could not take time to appreciate each map, and also nights became so short, but I think I never enjoy so much to make maps in ne month !
Looking forward for next year challenge !

DEV Community: Raymond Lay

Seamlessly Compare Maps on QGIS with the QMapCompare Plugin

Introduction

Installation

Usage

Comparison Methods Overview

Mirror View

Split View

Lens View

Practical Use Cases

Conclusion

Retrieve satellite earth observation images easily with QGIS JAXA Earth API Plugin

Abstract

JAXA Earth API overview

The use of QGIS JAXA Earth API Plugin

1. On QGIS and add OpenStreetMap basemap

2. Install JAXA Earth API Plugin

3. Plugin use example

At last

Get started with PyQGIS 03 - Manipulate vector layers with QGIS python console

1. Open script editor of Python Console

1.1. Open Python console in QGIS

1.2. Open Script Editor

2. Vector Layer related commands

2.1. Retrieve target layer by name

2.2. Retrieve layer extent

2.3. Retrieve layer extent

2.4. Retrieve the number of features of the target layer

2.5. Retrieves vector layer fields

3. Check output PyQgis class and its methods, a good pratice to make you grow up in PyQGIS

Solving QGIS plugin conflict

Way 1 : Turn off one of contentious plugins

Way 2 : avoid using utils.py (for plugin developers)

Get started with PyQGIS 02 - Manage layers with QGIS python console

1. Open script editor of Python Console

1.1. Open Python console in QGIS

1.2. Open Script Editor

2. Layer related commands

2.1. Import layer from file

2.2. Import only a part of features from file

2.3. List layers

2.3. Retrieve a layer by name

2.4. Remove layer

3. The use of QgsProject class to manage layers

Get started with PyQGIS 01 - Some basic commands with QGIS python console

1. Open Python console in QGIS

2. Run first commands

2.1. Hello world command

2.2. Get map canvas scale

2.3. Set map canvas scale

3. Understand commands and PyQGIS library

3.1. center to retrieve center point of map canvas

3.2. extent where canvas extent can be retrieved

4. First conclusion of PyQGIS approach

Remark:

Get started with QField cloud

What's QField?

And QField cloud?

QField sync to manage field projects

To summarize QField work architecture

1. Setup

2. Use case: Locate vending machines with QField

Prepare project layers on QGIS and push to cloud

Survey with QField

Get surveyed data on QGIS

3. Issues encountered

[enhancement] detect appropriate upload/download way

Dropping feature on QField device may not be detected when synchronizing in QGIS

My first #30DayMapChallenge

30+6 maps completed

Making maps with open tools

A great opportunity to do unusual maps

A great opportunity to try new tools

Conclusion

Related links