1

Space Syntax · Depthmap · Visibility Graph Analysis (VGA) tutorial Download depthmap software: http://archtech.gr/varoudis/depthmapX/ Simple online tutorial with dataset: http://otp.spacesyntax.net/software-and-manuals/depthmap/building-spatial-model/ Remember that running space syntax analyses is an iterative process. Try one design proposal. Run analysis. Edit footprint. Re-run analysis…

This tutorial has 6 steps. Step 1. Create Depthmap file Step 2. Create visibility graph Step 3. Fill grid Step 4. Analyse visibility graph Step 5. Look at results Step 6. Export figures Step 7. Additional analyses Appendix: What do space syntax measures mean Using Depthmap: General tips & shortcuts By Beatrix Emo: b.emo@gess.ethz.ch

2

Step 1. Create Depthmap file àPrepare a building footprint plan

Each building should be a closed polygon Put a boundary line around your footprint: the visibility analysis will include areas inside the boundary line. Keeping the boundary line as small as possible will mean the analysis will run faster. Decide whether you want to have an analysis that measures: - accessibility ie. canals are treated as buildings. This makes sense if you are

investigating how people will move around your plan OR - visibility ie. canals are treated as open space. This makes sense if you are

interested if visibility relationships only. You can of course run both analyses! This requires importing 2 different dxf plans. TIP: Make sure you have set the correct units on your CAD file, as depthmap uses the same units. TIP: If any of the polygons are not closed, the visibility analysis will not recognise the boundary and will compute it as open. This is very easy to see once you “fill the grid” in step 3.

à Export footprint as .dxf àImport .dxf into Depthmap Open Depthmap File-New (always!) Map-Import

You have now imported the .dxf into Depthmap and should see the footprint on the main window (“Map view”).

TIP: If depthmap crashes when you try and import your dxf, it may have too many classes/layers. You can test whether this is the case by opening a simple dxf (eg the one in the online tutorial mentioned at top of page) and make sure that a simple dxf file can be imported without problems.

àSave .graph file File-Save.

You have now created a .graph file with your footprint.

3

Step 2. Create visibility graph à Create visibility graph Tools-Visibility-Set grid

The “Set grid properties” window pops up

Choose an appropriate grid

The grid spacing that is offered by default is one that will compute quickly. However it is often too coarse for presentation. TIP: Choose the default grid spacing to begin with, run the analysis, then decide how fine you want your grid spacing to be.

“OK”

You have now created a visibility graph.

4

Step 3: Fill the grid à Fill the grid Click the fill icon in toolbar. Click on the space to be analysed.

The space to be analysed goes grey.

Note that, depending on your project, you might have to connect parts of your project that are otherwise disconnected. You can tell if this is the case, according to whether you have to use the “fill” icon more than once to cover all the usable space in your system. If you do, then you will need to link the spaces, so that the analysis treats the system as one space (and not two). This will require an additional step 3B:

- select the “link” icon - click on a space on one side of the space to

be connected - click on a space on the other side - the 2 spaces should be connected with a green line - if you want to delete 2 spaces that are connected with a green line, follow

the same procedure as above, only using the “unlink” tool instead

5

Step 4: Analyse visibility graph à Analyse visibility graph Tools-Visibility-Run Visibility Graph Analysis. Typically the below options are selected. “OK”

6

Step 5. Look at results The analysis you ran now shows in the “Attributes” window, on the left hand side of the screen. By clicking on each “Attribute”, the map view changes. What do the attributes mean: see appendix You might want to run: Visual Integration HH Visual step depth Isovist analysis Step 6. Export figure Edit-Export screen. This allows you to save the current view as an .eps or .svg file.

TIP: You want to change the background colour? View-Background. Choose your colour (eg. white). Click “OK”. Then click once anywhere on the screen.

7

Step 7. Additional analyses Visual step depth You may also want to run additional analyses, such as

- Visual Step Depth - Other forms of step depth

Select a pixel (you can also select a group of pixels by dragging across them with the select arrow) Tools-Visibility-Step depth-Visibility step

Figure. Example visual step depth

TIP: You want to change the colour scheme? Go to: Window-Colour range. You might want to reverse the sliders, so that spaces that are close to the highlighted location are red.

8

Step 7. Additional analyses (cntd.) Isovist analysis You may also want to compute individual isovists for relevant places. Select the isovist button from the toolbar (looks like yellow flower)

Choose whether you want to compute a full or partial isovist (I recommend 360 degree isovist)

Figure. Example isovist Note that you can compute overlapping isovists for multiple locations. These are then shown in different colours on the screen

9

Appendix: What do space syntax measures mean? Choose your analysis to match your question. A Visibility Graph Analysis (VGA) will tell you something about visibility relationships between spaces in your project. Visual Integration HH tells you how visually connected all spaces are in the footprint. Visual step depth tells you how many ‘steps’ it takes to cover the entire area, where the ‘steps’ are measured by how far you can see. (Note you can also compute step depth according to metric and angular displacement). An Isovist gives you a 2D polygon corresponding to the viewshed at that given point. This is relevant for an in-depth exploration of a specific location.

10

Appendix: Using Depthmap: General tips & shortcuts

o Use a mouse with a scroller (the zoom function does not work so well with a Mac mouse)

o Right-click to pan/drag

o Hover over a line to see the value of the parameter.

o File menu greyed out? Make sure the “Map view” window is selected. (The

“Map view” window can become de-selected when you switch back to Depthmap from a different programme)

o Depthmap crashes when you import dxf? Test a simpe dxf to make sure you

have downloaded depthmap correctly (eg. simple axial dataset in online tutorial). If that opens fine, reduce the complexity (eg. try removing excess layers/classes/size) of the dxf you are trying to import.

o Many shortcuts common for other drawing software aren’t available for

Depthmap running on iOS.

o Change colour scheme using Window-Colour range. Try Equal range and Depthmap Classic. “Apply all” selects the same colour range for all the analysis (it is important to export graphics that have a consistent colour scheme!).