depthmapX: visual and spatial network analysis software

At the building or small urban scale, depthmapX can be used to assess the visual accessibility of a place in a number of ways. It can produce point isovists, (polygons that represent the visually accessible area from a location) and isovist paths that show how the view changes when moving through a space. 

Isovists are the core element behind Visibility Graph Analysis (VGA), acting as the joining mechanism that converts a dense grid to a graph of intervisible points (a visibility graph), which may then be analysed using various graph measures. depthmapX provides local measures of visibility such as the isovist area and perimeter but also global ones quantifying building traversal and space centrality.

VGA can also be used as the core of an agent-based analysis. In this type of analysis, a number of software agents representing pedestrians are released into the environment. Each software agent is able to access the visual accessibility information for its current location from the visibility graph, which informs its choice of next destination. 

depthmapX allows for simulating different types of pedestrian behaviour by providing various ways for an agent to choose where to walk, such as towards larger spaces, long lines of sight or parts of their view that are occluded. The paths of the agents and their numbers passing through gates can be counted, and compared to actual behaviour of pedestrians passing through gates.

At the small to medium urban scale, depthmapX can be used to derive an axial map of a layout. This means it can derive a reduced straight-line network of the open space in an environment. The axial map has been the key analysis method of space syntax research for many years, but the mathematical derivation of it is novel. 

The automatic derivation within depthmapX allows an objective map for researching spatial form and function. Once the map has been generated, it may be analysed using graph measures, and the measures may be transferred to gate layers in order to compare with indicators of pedestrian or social behaviour. For larger systems where the derivation algorithm becomes cumbersome, pre-drawn axial maps or downloaded maps (such as road-centre lines) may be imported.

Axial maps can also be converted to segment maps by breaking down long axial lines into a sequence of segments that lead from junction to junction. These may be analysed using a variety of techniques that accumulate depth, such as the degree of angle change from one segment to another, metric distance, or segment steps. Examples include the calculation of the number of shortest angular paths through a segment, or the average metric distance from each segment to all others.

depthmapX can import pure geometrical data such as floor plans or line-centre maps. which may then be converted into spatial networks. They can also be converted directly into existing networks such as VGA, axial maps and segment maps. The software provides an interface for exploring and modifying these networks by representing them as geometries but also by displaying the various parameters associated with them. Finally, it allows for limited extensibility and combination of the various measures by providing a simple scripting language called "salascript".

Project Lead
Dr Tasos Varoudis

Developer
Dr Petros Koutsolampros

Original creator of Depthmap
Alasdair Turner

Past developers
Eva Friedrich and Christian Sailer

• See an up-to-date list of contributors

EPSRC Platform Grant: Space, Technologies and the Design of the Built Environment

UCL and Space Syntax Limited have developed a Space Syntax Online Training Platform to facilitate the dissemination of Space Syntax principles, methodologies and software. A brief guide to starting to use Depthmap can be found via GitHub.

• For news, release announcements, and relevant discussion subscribe to the UCL Depthmap mailing list.
• Download the current version of depthmapX.

Tasos Varoudis

Many features are covered in this tutorial by Joao Pinelo. You may also find tutorials for 7.12.00 and 8.15.00 useful.

Version 7.12.00 and 8.15.00 Tutorial

These tutorials are in PDF format. Note that they were originally prepared for version 7.12.00 and there are some very minor changes between 7.12.00 and 8.15.00 which are not covered. We hope that you will find no problems using them to learn version 8.15.00.

import geometry and visibility graph analysis (1.1MB)

import, generate or hand-draw an axial map, including linking and unlinking lines (1.3MB)

hand-draw a convex map, including linking spaces and analysing the map (0.8MB)

entering observation data, pushing values to layers, showing scatter plots, calculating correlation coefficients and exporting to spreadsheet programs (1.9MB)

discussion of advanced segment analysis topics in depthmap. Note that “Topomet” is included with depthmap and does not need to be installed separately (1.8MB)

The DXF files used in these tutorials are:

• gallery.dxf
• barnsbury_centre.dxf
• barnsbury_axial.dxf

Barnsbury original map data copyright © Cambridge University Press 1984, reproduced here with kind permission. Original drawings by J Hanson, digitised by A Turner.

In addition gallery.zip contains a VGA analysis of gallery.dxf, and example mif/mid files. 

This page stores all versions of the Depthmap Researchers’ Handbook. Please choose the version of the appropriate version of the handbook for your version of UCL Depthmap.

• Version 4.09:

Depthmap 4 – A Researcher’s Handbook (revision 1) (pdf)

• Version 4.06:

Depthmap 4 – A Researcher’s Handbook (pdf)

Scripts can be used to create user-defined formulae and simple graph measures.

Scripts from the SalaScript Manual

These examples are used in the SalaScript Manual.

total_depth.sala

Calculate total depth for each node in a VGA, axial or convex map

shortest_cycle.sala

Calculate the shortest cycle for each node in an axial or convex map

These scripts are teaching materials developed by Alasdair Turner and licensed under the CC-GNU GPL.

If you are a UCL Depthmap user, you may want to subscribe to the UCL Depthmap mailing list to exchange experiences with other users.

The software covers two separate models for spatial analysis; the Space Syntax model and the Agent model. These two models are theoretically different in spite of the fact that they agree on the principal relationship between space and society. They start from different representations, and they diverge at the point of modelling. The agent model represents an emergent process that leads to form aggregate patterns of movement activity. Through its ability to display movement data in relation to aggregate patterns of agents, Depthmap’s agents have proven to be an effective tool to simulate natural movement. Space Syntax builds on a synchronic reduction of spatial relationships in the built environment. Mapping this reduction into networks of longest and fewest lines, Depthmap’s axial and segment analyses are powerful methods for predicting to-movement and through-movement in cities. On the scale of buildings, spatial analysis using Depthmap can reveal relational structures that convey how social organisations occupy spaces. Depthmap is a platform that brings together these too models to be tested in an analytical approach. It also affords experimental and developer approaches.

The current usage of this software has proven to engage different types of academic communities that have a language in common with the notion of space. These communities range between planners, designers, social scientists, anthropologists, crime scientists, geographers, computer scientists and economists. In general terms, all what brings together the social and the spatial. In different contexts, spatial modelling using Depthmap can help forming assumptions about social behaviour in space and model spatial and social relationships. Moreover, Depthmap significance exceeds its common usage as an analytical tool to understand the built environment on different scales and go beyond that to act as a design and decision making support tool. The intelligent usage of software will deploy it in supporting design process with a knowledge-base that is suggested to make designs more responsive towards the real settings of the built environment. In simple terms, Depthmap is increasingly used as a tool for design thinking. By using it efficiently, the software helps on sparing time and cost, particularly on the scale of complex buildings and large scale urban planning.

The plans to make this software as an open-source platform along with the ongoing process of knowledge dissemination coordinated with Space Syntax LTD. will help adapt this software to accommodate different types of usage. It will allow for personalising the software to fit with certain expectations. It will also allow the integration of this software with other GIS and CAD packages, making it part of a wider community of planners, geographers and designers.