Importing GIS Data into Grasshopper

This tutorial will cover some basic techniques for importing GIS data into Rhino—using the Grasshopper plugin—in order to create a 3D site model with basic building masses. This method generates NURBS geometry in Rhino, allowing you to use features like Make2D to export vector graphics.


Required Components

This tutorial uses the TT Toolbox plugin for Grasshopper to read Excel spreadsheets.
TT Toolbox can be downloaded here: link

PREPARING DATA IN ARCGIS

This exercise uses a building footprint shapefile and visualizes the height of the buildings by extruding with height data in the shape file’s attributes.

For this exercise, we will be using the building_0715.shp shapefile found on the M Drive (DUSP GIS Data Drive) at the following directory path: M:\US_Cities\New_York_City\Base_Data\BUILDINGS\building_footprints_July2015

1. Open ArcMap. (You will find it in your start menu under Programs > ArcGIS > ArcMap)

2. Add the Data to the map. Once you’ve added your data, it will appear in the preview window.

3. Using the selection tools, highlight the area you are looking to visualize.

4. Export Selected Data to a new Shapefile. Right click on the data layer and Data > Export Data...

Make sure that the pull-down menu at the top of the export dialog box is set to Selected records, pick a location to save the file, and set the file type to Shapefile.

PREPARING ATTRIBUTE DATA IN EXCEL

5. Open Microsoft Excel.

6. Open the exported shapefile database (DBF file extension). Navigate to the folder where you exported your shapefile of selected building footprints, and open the file with the .dbf extension. If you do not see this file in the Excel Open menu, make sure the pull down menu for visible filetypes is set to “All Files”.

7. Save As this file as an Excel Workbook (.xlsx extension).

IMPORTING GEOMETRY DATA INTO GRASSHOPPER

8. Open Rhino 5. Make sure your units are set to US Feet.

9. Open up Grasshopper.

10. Load Building Footprints with the Import SHP component. Create a File Path component, an Import SHP component and a Curve component. Right click on the File Path component and use the Set One File Path command to link to the exported shapefile (.shp file extension).

11. Convert Curves to Boundary Surfaces. Connect the Curve component to a Boundary Surface component. This ensures that footprints with nested curves (courtyards) are only counted as a single item.

IMPORT ATTRIBUTE DATA INTO GRASSHOPPER

12. Connect to Excel spreadsheet. Locate the attributes spreadsheet with a File Path component. Right-click the File Path component, choose Set One File Path, and choose the Excel workbook you saved earlier.

13. Import data from Excel Spreadsheet. Connect the File Path component to a Read Excel Sheet component (from TT Toolbox). Connect the File Path component to the [Fp] input, and create a Boolean Toggle component (under the first component tab, Params > Input) and connect it to the R? input.  Set the Boolean Toggle to True to get the Read Excel Sheet component to import the Attributes file.

14. Copy the Excel data into a Data component.  Create a Data component and connect the Columns (C) output of the Read Excel Sheet component to the Data component. Right-click on the Data component and select Internalize data. While this step is not necessary, it will embed the data into the Grasshopper file and speed up the calculation process.

15. Extract Height Data. Create a Tree Branch component (from the TT Toolbox plugin) and connect the Data component to the Data Tree (T) input. Then, create a Number Slider of integers, and connect it to the Tree Branch component’s Branch Index (i) input.  Create a Split List component, and connect the output of the Tree Branch component to the List (L) input. Create a Panel  or Number Slider component with the value “1” and connect it to the Splitting Index (i) input. Finally, create two Panel components and connect them to the (A) and (B) outputs of the Split List component.

You should now see the Field Name in the panel connected to (A) and the values in the panel connected to (B). Changing the slider connected to the Branch Index will change between all of the fields (the columns from the Excel file), and “45” should be the field NumFloors.

EXTRUDE BUILDING FOOTPRINTS

16. Calculate extrusion height from number of floors. Create a Multiplication component and connect the (B) output from the Split List component (the values for number of floors) to the (A) input of the Multiplication component. Create a Number Slider and connect it to the (B) input of the Multiplication component. This will be your typical floor-to-floor height, which is around 12 to 14 feet for NYC. Create a Unit Z Vector component and connect the Multiplication output (R) to the vector’s input (F) to make sure we are extruding vertically.

17. Extrude building footprints. Create an Extrude component, and connect the surfaces of building footprints from the Boundary Surface component’s (S) output to the Extrude components Base (B) input. Then connect the Unit Z Vector’s output (V) to the Extrude component’s Direction (D) input.

18. Bake geometry into Rhino. Right click the Extrude component and select Bake.


Credits

Material for this tutorial is adopted from materials by the Columbia GSAPP.


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