Difference between revisions of "Os tools for os"

Revision as of 03:12, 28 June 2011

This page is intended as a central location for ideas feeding into creating open source tools for interacting with Ordnance Survey data / products.

Astun Technology and Faunalia are working on a set of tools to convert Ordnance Survey's GML based data sets to PostGIS or Shapefile.

OS MasterMap loader

A Simple script for loading OS MasterMap into a variety of formats including PostGIS, Shape, TAB etc. Written in Python and based on OGR.

Source code and download available on GibHub: https://github.com/AstunTechnology/osmmloader

Future enhancements

Managing Change only Updates
Postgres SQL to post process data to improve comparability with common client software
Creation of a classification column to make styling features easier
SLD and .map files to style the data

QGIS Plugins

Feel free to add possible features here for a QGIS plugin to allow users to easily interact with OS products

Importing OpenData

A nice typical process for users to follow to download OpenData would be:

Select the required data from the OS OpenData download page, enter details and wait for email
Paste contents of email into QGIS plugin
Plugin downloads all nessisary files mentioned in email and processes them

The data processing would generally consist of unzipping the data into a data type specific subfolder of the users's "OS Data Library" and then doing some data specific pre-processing.

Data specific pre-processing

The following tasks would be carried out on various different data types during the import process

Vector data

The following are changes to the GML/GZ data such as used for MasterMap. With these changes, QGIS can style text in the "standard" OS manner.

Translate OS "orientation" field (integer angle in 1/10 degrees) to "angle" as a float. [angle = orientation / 10]
Translate OS "font" field (integer in the range 0 to 3) to "qfont" as a string. [The string value is the name of the font on the local PC]
Translate OS "anchorPosition" (integer in the range 0 to 8) to "qPosition" as a string. [The string value is the QGIS position string, e.g. Above Left]

For OpenData, the VectorData District technical specification says that the data is in GML 3.1.1, but it is actually delivered as shapefiles. VectorData Local is however supplied as GML (GZ), but specified as 2.1.2.

"ORIENTATIO" always seems to be zero - should we just remove the attribute? It is also described in the VectorData District technical specification as being 0-359, so is different from the
"FONTHEIGHT" is described as points rather than map units for MasterMap. Simply using these values as map units results in too small text - possibly scale them?
"FONTCOLOUR" is a numeric field. The technical guide specifies standard colours, so these could sensibly be translated to standard QGIS colour strings. [1 = Black, 2 = Blue, 3 = Green, 4 = Dark Blue]
"FONTTYPE" is a numeric field giving an indication of possible font style. This could also be translated to a string specifying a local font. [OS suggestions: 1 = Corbel, 2 = Corbel bold, 3 = Arial]

Raster data

Create new or update existing .VRT layer of the raster tiles (VRTs are virtual raster layers that make multiple tiles look like one big tile)
Create new or update existing vector coverage layer (the vector coverage layer could be a square for each downloaded tile with an action set to open the given tile when a user clicks on it)
Image pyramids?

PostGIS Support

Would be nice:

Plugin sets up a PostGIS database easily without much user intervention
Plugin imports data (probably in chunks) into the database, taking care not to make duplicate features
Plugin handles change only updates
Plugin handles spatial index creation and database maintenance

General

Plugin keeps track of the last time each dataset was updated and possible lets the user know when updates are available

Ability to "backup" the library and settings, allowing the dataset to easily be transferred to another machine

Other

A gazateer plugin to be able to easily type in a place name to get QGIS to zoom to that location

@@ Line 33: / Line 33: @@
 The following tasks would be carried out on various different data types during the import process<br>
+==== Vector data<br> ====
+The following are changes to the GML/GZ data such as used for MasterMap. With these changes, QGIS can style text in the "standard" OS manner.
+*Translate OS "orientation" field (integer angle in 1/10 degrees) to "angle" as a float. [''angle = orientation / 10'']
+*Translate OS "font" field (integer in the range 0 to 3) to "qfont" as a string. [''The string value is the name of the font on the local PC'']
+*Translate OS "anchorPosition" (integer in the range 0 to 8) to "qPosition" as a string. [''The string value is the QGIS position string, e.g. Above Left'']
+For OpenData, the VectorData District technical specification says that the data is in GML 3.1.1, but it is actually delivered as shapefiles. VectorData Local is however supplied as GML (GZ), but specified as 2.1.2.
+*"ORIENTATIO" always seems to be zero - should we just remove the attribute? It is also described in the VectorData District technical specification as being 0-359, so is different from the
+*"FONTHEIGHT" is described as points rather than map units for MasterMap. Simply using these values as map units results in too small text - possibly scale them?
+*"FONTCOLOUR" is a numeric field. The technical guide specifies standard colours, so these could sensibly be translated to standard QGIS colour strings. [''1 = Black, 2 = Blue, 3 = Green, 4 = Dark Blue'']
+*"FONTTYPE" is a numeric field giving an indication of possible font style. This could also be translated to a string specifying a local font. [''OS suggestions: 1 = Corbel, 2 = Corbel bold, 3 = Arial'']
+<br>
 ==== Raster data<br> ====