Export from QGis to CAD¶

An algorithm has been created by Selvarani, to see the whole process click here:
https://redmine.auroville.org.in/projects/gis/wiki/Automatic_export_from_QGis_to_dxf

QGis Graphical Modeler: An algorithm to automatically export data directly from Gisaf to .dxf format (CAD)¶

• Login to PostGIS

• Directly from the Gisaf server, load all the layers which need to be converted into .dxf format

• Go to Processing Menu, click on “Graphical Modeler” (or Ctrl+Alt+G)

• The “Model Designer” window will open:

The final model will look like this:

Below, the explanation on how the algorithm has been created.

• An input to the algorithm is needed: go to “Inputs” tab and double click on “Vector Layer”

The window “Input Vector layer Parameter Definition” will open:

• in “Description”, enter “Input Vector layer”
• in “Geometry type” select “Any Geometry Type”
• Click “Ok”

Input is created as above.
As a second step, features need to be filtered, because some layers have different “Status” (E, D, F, etc. as defined in CSR Geomatics CAD Layer Naming Standards):

• in the Algorithms panel, type “filter” in the Search Box: this way, all existing algorithms related to “filter” will be listed
• double click on “Feature filter”

“Feature filter” window will open:

• Click on ‘Add output filter’ icon

• Click on expression button to write an expression for the filter.

• The Expression dialog will open, type the criteria for defining the filter, e.g. “STATUS”=’E’

• Click “Ok”: the expression is added in the table of “Outputs and filters” as below.
• In the field “Output Name”, type in the output as ‘E’.

• Repeat the same steps for all other status (Like D,F,N,T,M and X)
• Click on the “Input layer” button and select “Model Input” in the drop-down list, it will change to “Input Vector layer”. Click on “Ok”

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The model will look like below:

As the input layers were taken directly from Gisaf server, where their CRS is WGS 84-EPSG:4326, all outputs need to be reprojected in TM AUSPOS CRS, because the CAD overall survey map is in TM AUSPOS:

• Go to “Algorithms” panel and type “reproject” in the Search Box: this way, all existing algorithms related to “reproject” will be listed
• Double click on “Reproject layer” under “Vector general”

The “Reproject layer” dialog will open:

• In the “Description” box type “Reproject layer ‘E’”: this will reproject only the features with status ‘E’

• In “Input layer” drop-down select “Algorithm Output”, click on the related box and a list of all available algorithm outputs will appear.
• In “Using algorithm output” select ““E” from algorithm “Feature filter””

• In “Target CRS” select “USER;100028-TM AUSPOS”

• Click “Ok”. The model will look like below:

• Follow the same steps for all the status (N, D, F, T, M, X), from “Reproject” onwards

Once finished, the model will look like this:

The final step of the algorithm is to convert the outputs to .dxf format:

• Go to “Algorithms” panel, type “dxf” in the Search Box: this way, all existing algorithms related to “dxf” will be listed,
• Double click on “v.out.dxf” from “GRASS”

• The “v.out.dxf” window will open. In “Description” type “v.out.dxf ‘E’”
• In “Name of input vector map”, click on the button and select “Algorithm output”

• In the drop-down list, select ““Reprojected” from algorithm “Reproject layer “E””

• In “DXF vector” type “DXF ‘E’”. This means that the dxf is the final output of the algorithm

• Click “Ok”. Now the model will be as below:

• Repeat the same steps for all other status.

The algorithm is now ready to convert QGis layers to .dxf format.

• To save the model, click on “Save”
• “Save Model” window will open, give a name to the model (e.g. ‘Export SHP to DXF’) and save it.