Wikipedia:Graphics Lab/Resources/QGIS/Reprojection

 —Contribute to this tutorial by completing one section welcome !

Projection (0%)

 In progress

• Raster layer to Robinson

Introduction

Source projection, target projection

First, you have to find the definition of your source projection/file. It's a kind of long equation which definite the properties of each projection. So:

QGis (1.7) > File > Project's properties (a window pop up) > tab 'Coordinates Reference System (CRS)'

Secondly, you have to find the definition of your target projection.

QGis (1.7) > File > Project's properties (a window pop up) > tab 'Coordinates Reference System (CRS)'

>> Select your target projection* > copy the definition (the long equation) >

>> ?create a personalized projection.?

QGis (1.7) > Raster > Warp (reproject) > (a window pop up)

> fill the fields witht he source SRS, and the target SRS > open in canvas > run > get the result.

Reproject a raster layer

Qgis, trouve la définition de Lambert : propriétés du projet > système de coordonnées de référence > sélectionne Lambert et regarde sa définition dans la petite fenêtre située sous la liste. Copie cette déf puis crée une projection personnalisée avec cette déf. Puis Raster > projection avec cette déf personnalisée (comme tu avais fais pour Robin). Je ne coche rien d'autre, je fais OK et le fichier reprojeté est créé. Ça marche pour etopo1 et pour les srtm fusionnés.

Reproject a vector layer

Raster to Vector (polygons) (0%)

• Covert to vector
• Edit polygons
• Gdal_contour (fr)
• Using TheGIMP (fr)

Concept: Use an elevation GIS file, a discrete black & white colormap, and the Print composer to output one 1500px/1500px black & white png by altitude (0m, +200m, +500m, etc, name the png accordingly!). This by a cycle such as 1. editing the map color, 2. actualizing the Print composer, 3. outputting the new png. Then use Inkscape to vectorize : load all png, align them, vectorize each using 2 colors + delete background. Color each vector polygon level (0m, 200m, ...) as need.

Introduction

QGis don't convert raster polygons into vector polygons. It does contours, but which have no fill, and thus, are not suitable.

QGis cycles

Inkscape cycles

Add a plugin (100%)

 — concept ok, screenshot welcome (Fetch python plugins' window).

Plugin in the repositories

Most plugin are in the repositories.

1. QGis > Plugins > Fetch python plugins (a window pop up)
2. > tab "Repositories" > Add 3rd party repositories > ok.
3. > tab "Plugins" > Filter: [YourKeyWord] > (if you see your plugin: click) > Install plugin

Our important plugins: Shaded relief ; SimpleSvg,

Plugin not in the repository

Extended content

:This section is about adding a plugin not available through QGis (1.7) > Plugins > Fetch plugins, and thus to install handily. We take the case of QGis SimpleSVG plugin. Download the plugin > Unzip it. Cut-Paste the folder in for Linux : in /home/YOURUSERNAME/.qgis/python/plugins/ (paste me here!) for Windows: somewhere in c:/documents and settings, within the QGis' python plugins folder. QGis (1.7) > Plugins > Manage plugins > QGis Plugins Manager (pop up)¹ > search key word (SVG) > check the good plugin + ok >> Open a/some vector layers or a project with them > >> Plugins > Find your plugin: "Save as SVG" > Save as SVG > Choice your ouput place. ¹: this window also provide you the address of your plugin directory ! SimpleSVG currently save the QGis' screen as a SVG with the correct layer division. This save us a lot a energy for later Inkscape work, especially colorations. SimpleSVG is a plugin currently under developement, Richard Duivenvoorde is looking for ideas for improvement.

Links

The table above has links to various tutorials and resources which can help in the creation of Wikipedia maps from digital georeferenced data (GIS).

== (I should read before writing) == Read: /Didacticiel d'installation de winGRASS GIS http://www.qgis.org/wiki/Users_Corner En:User:Captain_Blood/GMT_Example Travaux impressionnant: Ombre: SRTM3 v.2 + en:3DEM Geocoded File:China edcp location map.svg, part of the +500 Location maps. Geocoded File:China edcp relief location map.jpg (with paralleles and lattitudes)