[Qgis-user] Atlas generation - help please

[Thomas Colley]

How about creating a polygon layer with a bounding polygon for all points per species? The polygon features would have the species name as an attribute.

 

You can then use this polygon layer for your atlas and use rule based styling to filter the points based on the species name attribute of the atlas feature.

 

A trigger could be used to keep the polygons up-to-date with the points if that’s an issue and the data is in PostGIS.

 

Definitely make for a nice case study!

 

Cheers

 

Tom

 

From: qgis-user-bounces at lists.osgeo.org [mailto:qgis-user-bounces at lists.osgeo.org] On Behalf Of Sergio Vignali
Sent: 02 September 2014 12:31
To: Alexandre Neto
Cc: QGIS User; john at jnecology.com
Subject: Re: [Qgis-user] Atlas generation - help please

 

Hi Alexandre,

you say that you know a way to do that with postgis,

please could you explain that?

 

All the best

 

Sergio

 

2014-09-01 22:42 GMT+02:00 Alexandre Neto <senhor.neto at gmail.com>:

Hello john,

The way the atlas work is the following. You prepare a layout, then you use one layer of the project as a coverage layer (full of features). When you export or print using the atlas toolbar, it cycle all features center/zoom to its geometries and print the map.

This would be useful to print some location maps for a few individuos from a species, to take to the field.

More, if your layer have some significant attritutes, you can use then in labels in your layout.  Even logos can be set.

Now,  you "problem"is slightly different. You want to see all points (say the all country or region),  of a specific filtered specie. If the points were completely disjointed, that is, no point of one specie ever overlay another, I can imagine a way of doing it by using atlas and storing the data in spatialite or postgis. Otherwise,  afaik there is still no way of doing it in qgis

I remember Nathan wodrow talking about creating a funtion to access the coverage layer attributes, that could be used in ruled based styling. This would allow you to do what you need with great speed.

Maybe he still can do it, or maybe you are able to sponsor that new feature.

Alexandre neto

Em 01/09/2014 17:47, "John Norton" <john at jnecology.com> escreveu:

Hi,

 

I was very excited when I saw that automated ‘atlas generation’ had been added to the map composer in version 2, but I cannot figure out how it works. The User Guide documentation is very brief and the terminology is difficult to comprehend. What is meant by ‘geometries’ and  why would I want an atlas of ‘geometries’? Can someone give an example of what it might be used for and how it would be set up? 

 

The reason for asking is because I would like to be able to automate the process of creating maps showing wildlife distributions. GIS is used widely in the UK and other countries for storing wildlife data, but until now in order to produce atlases we have used software such as DMAP and MapMate. To those not familiar with wildlife mapping the simplest possible dataset would be a number of records of one or more species, each with an X and Y coordinate. The data can be saved as a shapefile point data layer. Each record is therefore a feature. The data can be styled as ‘single symbol’ so that records with the same coordinates overlie each other when viewed. To see the distribution map for a particular species the data needs to be displayed as ‘rule based’ and a rule set up to filter the records for each individual species (e.g. “Species” = ‘Quercus robur’ filters out records of Pedunculate Oak). The resulting map can then be output to a jpeg in the usual way using Print Composer. This process is unworkable, however, because every time a different species is viewed or output, the filter needs to be manually changed. The only other option at present is to split the data into separate layers, one for each species, so these can be turned on or off as needed. This is workable for small numbers of species but not for 1000+ species as would be required for a flowering plant atlas for example. So is creating a species distribution atlas possible using the atlas generation dialog in version 2, or is ‘atlas’ being used in a completely different sense here? And if it is not possible, is anyone working on a solution? It would be of huge benefit in the nature conservation world if so.

 

John Norton, Gosport, UK

 

 

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-- 

Sergio Vignali

 

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