GIS

h1. Working with Gisaf

h3. Survey data

Raw survey data are contained in CSV files, typically downloaded from surveying instruments.

See more information of the process for the survey data (including a flow diagram) at [[Gisaf workflow]]

h1. Survey data

h1. Importing point data (TS and RTK) to GISAF - %{color:RED}  TO BE CHECKED%

# *Gisaf Admin > Basket > Survey data > "Project" > "surveyor" > TS/ RTK > upload > import.*

# *Auto import of Raw points data* (changes from Raw to Shapefiles, the point files)

  In GISAF Admin > Other> Project > select the project for which you want to import the data > with selected > Auto import to GIS...

h2. Import basket

Gisaf provides an "import basket" dedicated for raw survey data, which is generated by land survey equipment (Leica's Total Station and RTK). 

These are CSV files, like:

<pre>

100081,370633.969,1327742.157,51.187,,,

100083,370628.876,1327702.913,51.565,T52,,

100082,370628.729,1327720.019,51.261,T52,,

100081,370633.969,1327742.154,51.179,,,

100083,370628.876,1327702.913,51.565,T52,,

20800,370633.969,1327742.154,51.180,,,

20801,370618.795,1327713.172,52.817,E30,,

20802,370623.674,1327711.436,51.283,B35,,

20803,370619.314,1327713.407,51.383,B35,,

</pre>

Each category (5th column) must be defined in the Category table (see [[Categories]]).

h2. Organization of the raw survey data basket

The basket should be organized in a directory structure:

- Project name (these can be themselves put in a hierarchy of (sub)directories)

- Surveyor's organization

- Equipment (eg. TS, RTK)

- Survey files (eg. @Our_project-Some_comment-2018-02-23.txt@)

h3. Format of the survey file names

<pre>

Our_project-Some_comment-2018-02-23.txt

</pre>

The date of the survey follows the ISO date standard: @YYYY-MM-DD@.

h2. Import to the database

When importing raw survey data files to the database, Gisaf does 2 steps as described below.

It's worth noting that, in this process, no reprojection is done.

h3. Feed the raw_survey table

Each point of the imported raw survey data file is inserted to the raw_survey table:

# Creation of a Point geometry: the raw_survey table has a geometry column for a single point (@geom@) with x,y and z coordinates

# Save the @id@ of the original point *to the @orig_id@ column*

# *A unique @id@ is computed* from the following fields: @id@, @project@, @equipment@, @date@

# The project is saved in the @project_id@ column

# The surveyor identification in @srvyr_id@

# The date of survey is saved in the @date@ column

# The accuracy is tagged in the @accur_id@, according to a mapping defined in the @accuracyequimentsurveyormapping@ table, which depends on the surveyor and equipment

# The category of the point

h3. Feed the @RAW_V_*@ tables

From the @raw_survey@ table, each point is then copied to its respective @RAW_V_@ table, with basically the same information.

These tables (which should be created manually or with the admin notebook called @create_tables@, as of today's writing), only contain points.

The project is saved along: see below.

h2. Import the points

For categories that define points (opposite to lines and polygons, which require _line work_ carried over in CAD or in a GIS software, see [[Line work]]), the points can be imported automatically to their final destination: the @V_*@ tables.

Note: in this process, the geometries are reprojected.

h2. Auto import of the points

The points found in the @RAW_V_*@ tables can be imported automatically, project per project, the project page of the admin interface.

h2. Import of the line work (lines and polygons)

h2. See [[Line work]] - *%{color:RED} to be written%*

The shapefiles generated manually (line work) should be put in the project's basket, and imported from it.

h1. Documentation - Tags retained after re-import of same geometry

Documentation - Tags retained after re-import of same geometry

The linework for infrastructure survey carried out by Eric Chacra in May 2020 was originally imported with a problem of ambiguity in the "Accuracy" table and in the "Accuracy" table.

The result was that lines did not inherit the attributes survey date, accuracy, equipment, surveyor.

Nevertheless lines were displayed on the Gisaf map, without these attributes, and tags were given to some of these lines.

The values for the two tables ("Accuracy", "Accuracy") have been corrected, ambiguity resolved.

The lines in the layers V-ELEC-UGND------E and V-COMM-CABL------E have been then reimported, the attributes have been properly assigned, and the tags have been retained.

4 August 2020

h1. Access to data

h2. Connection to server directly from CSR

To connect to the server directly without going through Aurinoco server, the correct url is

http://gis.csr.av

h1. URL for showing information of a feature

Gisaf can show information about a feature when it loads. This allows other softwares (Redmine, etc) to create links that bring their users to the feature on the map, and display the information related to it.

When Gisaf finds that the URL matches a certain pattern, it tries to load the layer of that feature, find the feature, zoom to it and open the information panel.

URLs can be crafted according to this template:

<pre>

https://gis.auroville.org.in/map?show=<layerName>:<field>:<value>

</pre>

where:

* <layerName>: name of the layer (store). Example:

  * buildings from the "old" TDC building layer: @other_tdc.building@

  * cadastral plots: @other_avf.cadastral_avf@

* <field>: field name. Example:

 * id

 * plot

* <value>: value of that field

Full examples:

  * <notextile>https://gis.auroville.org.in/map?show=other_tdc.building:id:1370</notextile>

  * <notextile>https://gis.auroville.org.in/map?show=other_avf.cadastral_avf:plot:IR216</notextile>