School of Surveying and Spatial Information Systems

The University of New South Wales

 


 

A View from Seat System for the

Sir John Clancy Auditorium

 

By Andrew Hammond

 

Supervised by Assoc. Prof. A.H.W. Kearsley, Dr B.R. Harvey & Dr S. Lim

 

October 2004


Aims

Large price differences exist between tickets for ‘A Reserve’ and ‘C Reserve’ seating in theatres and concert halls.  Similar price differences exist between tickets for the various bays, stands and concourses of a sports stadium.  A computer model allowing prospective tickets buyers to see, virtually, the view from their desired seat before purchasing would have benefits for both patron and ticket vendor satisfaction.  This project aims to develop and prove a concept for a ‘view from seat’ system which could be applied to any venue at which tickets are sold.  It is hoped to prove the method adopted to accomplish this system would be able to be replicated for any location, be it a stadium or theatre of any size. 

Scanning the Auditorium

The scan took place on Wednesday the 7th of July 2004 at UNSW’s Sir John Clancy Auditorium, located in the upper campus and found as building C24 on the standard campus map.  A Leica HDS3000 High Definition Surveying Laser Scanner borrowed from SKM Consulting (http://www.skmconsulting.com/Markets/spatial/Field_Surveying.htm) was set up on a heavy duty tripod and levelled.  Using its combined horizontal/vertical fields of view of 360˚ and 270˚ respectively, it completed a single scan of the whole of the Auditorium at a horizontal and vertical point spacing of 100mm in about 40 minutes. 

The output of this scan was an .imp file where, if viewed as an interchangeable .as5 or .txt file, the data consists of a series of row entries.  Every scanned point takes up one row entry and contains a unique x, y and z coordinate set, and an unseen spectral colour value for the material that was represented. 

Figure 1: The Leica HDS3000 set up in the Clancy Auditorium

 

How Do You Create a 3D Model from a Laser Scan?

A combination of both Autodesk AutoCAD 2004 and Cyra Cyclone was used to fully model the scanned Auditorium.  The goal was to simplify the point cloud from the HDS3000 (some 490,000 points) into simple geometrical figures such as planes, boxes and curves.  Once done, the memory-intensive loading of the original point cloud was no longer necessary and where powerful computers with expensive Cyclone software were needed to view the Auditorium before modelling, average computers with simple dxf viewers were now all that was required to visualize the model of the Clancy Auditorium. 

Cyra Cyclone v4.1

This package enabled real-time visualisation of the Auditorium’s geometry, utilising three important 3D functions; pan, zoom and 3D rotate.  Modelling of the Auditorium was also able to be performed to a limited extent in Cyclone; 3D objects such as patches, cylinders and boxes were fitted to the limited number of corresponding physical features scanned by the HDS3000.  Walls and other simple flat surfaces were modelled using these functions.  See http://hds.leica-geosystems.com/products/cyclone5.html for more details on how these work.

Figure 2: The .imp file output from the scan as seen Cyclone

Of particular help was Cyclone’s ‘region grow’ function, which automatically fits a patch over a plane defined by three picked points and within tolerances which can be altered as desired.  This was quickly found to be the most effective way of modelling the flat side walls, but was limited in its application on complex objects such as fanned wall features or even the curved rear wall of the Auditorium.

Modelling the Point Cloud in AutoCAD

AutoCAD 2004 was useful for 3D modelling as it supports this capability by allowing objects such as polylines, 3D faces and polygons to be created whilst rotating a 3D orbit of the scan.  The patches created in Cyclone representing the walls appeared as 3D faces when viewed in AutoCAD, meaning that they could be rendered.  At this stage, all stairs and seats were created.  Initially modelled from dimensions obtained from the scan, both of these objects were created independently of the model and inserted in appropriate places.  This was possible as all stairs and seats were of common dimensions.  A ‘POINTS > BLOCKS’ LISP routine was then run, inserting the relevant block (i.e. the model of a single seat) at the appropriately selected scan point common to all seats; in this case I selected 945 points all corresponding to the top centre of the seat’s back rest.  Once a satisfactory model was achieved given the time constraints of the project, a final .dxf file was saved and was ready for examination from various seats. 

Figure 3: The model as seen in AutoCAD

Visualising the Model in ArcScene

The last step in the project was to examine the view from specified seats.  The final .dxf was imported into ESRI ArcScene and polylines and polygon layers were turned on. Note that without a very powerful graphics card it is impossible to navigate smoothly around a rendered model, only polylines can be visualised 'real-time'.  Now, a 3D navigation was possible of the modelled polylines; see my short movie below for a look around the Auditorium.

avi/Walkthrough.avi

The polylines provided the skeleton of the features, whilst the polygons were the solid colouring which was required for the final view from seat.  Simulated views from different seats were then possible, using the ‘zoom to target’ and ‘set observer’ functions.  These defined the centre of view, and the location from which the view was made, respectively.  The views from 10 chosen seats spaced out around the entire Auditorium (visit http://www.conferencing.unsw.edu.au/text/venues/clancy/clancy1.htm for a seating plan) were then created and saved as screenshots.  These were used for later comparison with photographs from the same 10 seats facing the centre of the stage.  

Figure 4: A (rendered) static view from seat U61 towards the stage in the final model seen in ArcScene 

Discussion of the Final Model

The sum total of the processes used to create a 3D model of the Sir John Clancy Auditorium was something which can usefully be compared to a working example of the view from seat concept put into commercial practice. Possibly the first such system to be made available on the World Wide Web can be found here http://home.seatbooker.net/pressreleases_02-03-11.htm

The method adopted for my thesis could be replicated and extended to any theatre.  Smaller and simpler theatres shaped more like a rectangle would be relatively straightforward to scan and model.  However, with increased simplicity comes a decreased need to visualise a view from seat.  Vice versa, a large venue such as a stadium would be very time consuming and difficult to model, but the usefulness of such a model would be greatly magnified.  The real advantage of a model such as the one created in this project is its spatial nature, which allows measurements, queries and even drawing layers to be made and manipulated.  For the method used in my thesis to produce a workable and detailed system, rather than just a model, more work would need to be done but benefits would exist over purely photographic methods.  However, a 360° photographic view is currently very easy to produce - see http://www.diynet.com/diy/hp_digital_photography/article/0,2033,DIY_13956_2274213,00.html for how to do this - and so would suffice for most view from seat purposes at the moment.  

The level of detail of the final product is a function of its purpose.  Entire theses have been written on accurately modelling objects like statues the size of a small car for heritage/cultural documentation purposes.  Many have concentrated on using complex TINs and NURBS to achieve a high quality digital representation of feature-rich objects preserving as many geometrical and visual details as possible.  Clearly, this amount of detail was not possible to achieve given the time constraints of this project.  Objects such as fanned wall features, roof recesses, a grand piano and flowers which are present in the Clancy Auditorium would have taken many hours each to model accurately.  

Conclusion

The use of laser scanned data such as that obtained by the Leica HDS3000 is limited only by imagination and the software technology associated with it.  Models with distances and layers able to be queried and manipulated are a great leap forward from current view from seat systems.  In the future, as automated modelling of scan data based on complex fitting algorithms becomes more advanced, a project such as this could be completed in a fraction of the time taken here.  It is envisaged that when such technology becomes available, full scans and models of sporting stadiums and other large seated venues would be feasible to produce.  The processes undertaken in this project, although limited because of their labour-intensive nature, could be replicated in any given location, at theatres or stadiums of any size. 

Further Information

For more information, please contact:

Dr B.R. Harvey
Email: geomatic.eng@unsw.edu.au

Mail:
School of Surveying and Spatial Information Systems
University of New South Wales
UNSW SYDNEY  NSW  2052
Australia

Phone: +61-2-9385-4173
Fax: +61-2-9313-7493
WWW: http://www.gmat.unsw.edu.au