Working with Gisaf¶

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)

Survey data¶

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:

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,,

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

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)

Format of the survey file names¶

Our_project-Some_comment-2018-02-23.txt

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

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.

Feed the raw_survey table¶

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

1. Creation of a Point geometry: the raw_survey table has a geometry column for a single point (geom) with x,y and z coordinates
2. Save the id of the original point to the orig_id column
3. A unique id is computed from the following fields: id, project, equipment, date
4. The project is saved in the project_id column
5. The surveyor identification in srvyr_id
6. The date of survey is saved in the date column
7. The accuracy is tagged in the accur_id, according to a mapping defined in the accuracyequimentsurveyormapping table, which depends on the surveyor and equipment
8. The category of the point

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.

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.

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.

Import of the line work (lines and polygons)¶

See Line work - to be written¶

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