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Export from QGis to CAD » History » Version 23

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Giulio Di Anastasio, 06/05/2021 17:17


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”



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””