Processing the Data and Programming the Interface

Processing the Data

At the beginning of 1996 several hardware systems were tested to explore the possibility to record, process and present multi medial data. A Sony Camcorder Hi8 system was finally selected to produce analogue sound videos. The hard- and software components of the video system Aviator Speed were used to digitise the videos. Unfortunately it is still not possible to produce well compressed video files in the MPEG (Motion Picture Group) format with an adequate quality for presentations. Therefore we stored the files in the Video for Windows format (*.avi), which is an uncompressed format and needs consequently a lot of storage space (a sound video sequence of 30 seconds is about 8 megabyte big).

By means of a standard photo camera with a 35 and 50 mm lens images were taken in the field and scanned afterwards with a scanner system from UMAX. Most of the files are stored as compressed *.jpg files, georeferenced background images are stored as TIF files (tagged image file). We also researched the possibility to generate so called Anaglyph Images on the basis of stereo aerial photos to produce a 3 dimensional impression of the landscape. We used the software PCI (see report95: "hardware equipment"), an image processing system which gave us the best results. Poorer results were achieved by means of Photoshop, which does not have an image georeferencing tool. The option to produce anaglyphs with ArcView will be researched in Winter 1997/98. The anaglyph process is based on the elimination of either the red channel or the green channel of a RGB (256 colours of a red, green and blue channel) images. By overlaying a red/blue image with a green/blue image there is a 3 dimensional impression if the observer uses glasses with a green filter for one eye and a red filter for the other eye.

Different polygon, line and point data were purchased from the state survey branch in Munich. The data had to be processed and transferred from the DXF (Drawing Exchange Format) format to the ArcInfo formats shape and coverages. Additionally landscape elevation models were bought, processed and transferred into grids. The raw data of the elevation models were also used to generate triangulated network models which can easily be moved in real time with a standard PC. The models were programmed with the Virtual Reality Modelling Language (VRML) to be displayed in Netscape Navigator Gold. To enhance the possibility for realistic simulations we decided to do some photo manipulations with Photoshop an generate an animated image sequence in GIF 84a format, which is small enough to be presented with the Netscape Navigator.

The entire data set for the Case Study Landscape Master Plan Burggen is 230 Megabytes. Following chapter describes the data structure of the GIS project:

Data structure of the digital Landscape Master Plan of Burggen (230 Megabytes)

Programming the Interface

To link all multi medial data to the georeferenced GIS environment we decided to use ArcView Version. 3.0, which runs on WIN 95 and WIN NT and has its own programming language, which is based on C++ and allows the user to alter the GIS surface according to his specific requirements. The performance of the basic module of ArcView was improved by the extensions Spatial Analyst, which comprises all functionalities of a raster GIS, it corresponds to the GRID module in ArcInfo. There are two more interesting extensions, whose performance for FORAM purposes will be researched in winter 97/98: the Network Analyst and the 3D Analyst, an extension which corresponds to the ArcInfo TIN module and will be released by ESRI not before end of 1997.

ArcView is an affordable and user friendly GIS, which is programmable (Avenue is the name of the C++ based programming language) and open for a wide range of external applications due to its Dynamic Data Exchange Technology (DDE) and Avenue´s Dynamik Link Library (DLL) on Windows. The Remote Procedure Control (RPC) works on all platforms to establish Client/Server relationships with other applications (ESRI 1997 "Using Avenue" p 205). ArcView costs about 1500 ECU without extensions and is well suited to do all necessary works on one system, like digitising, analysing and presenting the data digitally or as a hardcopy.

We programmed ArcView for the requirements of the Case Study Burggen. Following are some of the source codes (scripts), which control the ArcView Project.

Script to start a video by selecting the recording point in the map:

'Hotlink-Script, to start a Video
theView = av.GetActiveDoc
theTheme = theView.FindTheme("Videos")
thePoint = theView.GetDisplay.ReturnUserPoint
If (theTheme <> nil) Then 'Thema gefunden
theFTab = theTheme.GetFTab
theField = theFTab.FindField("Hotlinks")
If (theField <> nil) Then 'Feld gefunden
theRecs = theTheme.FindByPoint(thePoint)
If (theRecs.Count > 0) Then 'wenn Datensätze gefunden
Wert = theFTab.ReturnValue(theField,theRecs.Get(0))
If (Wert <> "") Then 'wenn Datensätze gefunden
system.execute("Mplayer.exe /play /close"++wert)
Else
msgBox.Info("Kein Eintrag gefunden","Abbruch")
End
Else
System.Beep
End
End
End

The scripts below open Nestcape Navigator and the WIN 95 Media player