Laser-Scan Ltd.

Software Product Specification

TVES package

Issue 2.7 7-May-1992
Copyright (C) $$year Laser-Scan Ltd
Science Park, Milton Road, Cambridge, England CB4 4FY  tel: (0223) 420414
Document "TVES SPS"                                    Category "SALES - Spec"
Document Issue 2.5   Clarke Brunt                      25-Apr-1991
Document Issue 2.6   Jon Barber                        03-Sep-1991
Document Issue 2.7   Jon Barber                        07-May-1992



The TVES package is one of 6 Laser-Scan DTM production and manipulation packages:


The TVES Package is designed to exploit a grid based Digital Terrain Matrix (DTM) held within Laser-Scan's Digital Terrain Image (DTI) format. It allows a customer to derive additional geographic measures such as slope, aspect and visibility information from the elevation data. The package also contains facilities to display grid based data in combination with vector geographic data in both 2 and 3 dimensional representations, and modules to allow conversion between grid (raster) and vector formats.


The TVES Package requires grid based data to be held in Laser-Scan's Digital Terrain Image (DTI) format, and vector data to be held in Laser-Scan's Internal Feature Format (IFF).


Data output and data conversion is to either the DTI format as grid representation or to IFF as vector representation.


Package TVES offers the following features:


The following computer hardware requirements are needed to run TVES.


TVES modules run under VAX VMS V5.4-3 (or later version, assuming continued upward compatibility by DEC), concurrently with other interactive and batch processes.

For the use of Motif on a VAXstation, the "DECwindows Motif" layered product from DEC is required. The "VMS DECwindows Developers Kit for Motif" is not adequate.

For the use of UIS on a VAXstation, VAX VMS Workstation Software (VWS) version 4.3 or later is required.

A minimum working set of at least 4000 pages is recommended. Larger working sets will help performance, particularly with large matrix files.

Laser-Scan's *IFF *Map *Processing package (IMP) and the MATRIX raster data processing package are essential. Laser-Scan's LITES2 interactive digitising and editing software running on the same workstation is recommended for digitising vector input data. LASERTRAK automated digitising is recommended for large numbers of input documents.


The minimum hardware and software requirements for any future version of this product may be different from the minimum hardware requirements for the current version.


TVES is a fully supported Laser-Scan standard software product.


Package TVES consists of the following component modules:


COVER determines which areas of the terrain surface are visible or hidden from the view of an observer. The observer may be positioned on or above the terrain surface, and may represent either a human observer, or a device such as a radio transmitter.

The input to the module is a Digital Terrain Model (DTM) and optionally a file with information on the heights of surface features. The output is a grid based intervisibility or cover map, that may be displayed in colour coded form on a graphics device, or manipulated using other TVES modules.

Both input and output data are held in a Laser-Scan Digital Terrain Image file. The main features of the program are:


The module DTICHECK is used to validate the data values in a DTI file. It is generally used to detect possible problems in a Digital Terrain Model (DTM). Checks are made for:

The checks may be carried out singly or in any combination.

Error output may be directed to either an IFF file, LITES2 command file, or ROVER command file. The two command files may be used to aid the interactive correction of height errors in the DTM.

MODULE DTICONTOUR (recontouring from DTM)

DTICONTOUR is a grid bilinear contouring program, using DTMs contained in DTI (*Digital *Terrain *Image) files. Contour output is to a Laser-Scan IFF format file.

DTICONTOUR offers the following features:


The module DTIVIEWEXTRA enables the IFF vector overlay options in DTIVIEW. These options allow data describing surface features (eg. rivers and woodland) to be drawn on a 3-D perspective or isometric terrain image.

The primary use for the option is for data verification, enhancement of the model, and for Geographical Information System applications which involve the combined presentation of vector and raster data.

Overlay facilities within DTIVIEW allow:


I2GRID is a module to convert data from Laser-Scan's Internal Feature Format (IFF) to Laser-Scan's Digital Terrain Image (DTI) format. In so doing the data is converted from a VECTOR to a GRID (raster) form; ie. the data in the input IFF file is rasterised.

In its rasterised form, the data may be manipulated and displayed using many of the modules that form part of the Laser-Scan TVES and MATRIX packages.

The module does not require a graphics device.

The main features of I2GRID are:


The module PROFILE is used to construct a series of path profile lines through a Digital Terrain Model (DTM). Typically, the origin of the profiles will be a base station, and the profile data will be used for radio frequency propagation analysis. Profiles are constructed either radially around the base station, or between each DTM node and the base station. Options are provided in the program to restrict profile generation to a rectangular area of interest, or to a sector of interest.

Input is a DTM, and optionally a series of clutter grid files, held in a Laser-Scan Digital Terrain Image (DTI) format. The DTM defines the elevation of the terrain surface, while the clutter grid file contains height information relating to surface features such as buildings, vegetation or water. Output is to a Laser-Scan vector Internal Feature Format (IFF) file.

Each profile is written to the IFF file as a separate feature. The bearing and length of the profile is stored in the IFF file, along with the x, y and z coordinates of the profile sample points. Additionally a clutter index value is stored for each sample point. The main features of the program are:


ROVER displays both grid based and vector geographic data. Output is to a Laser-Scan supported graphics device or colour electrostatic plotter. When using a graphics device the user may interactively interrogate and edit the grid data. The grid data may take the form of a DTI (Digital Terrain Image) file containing elevation, slope or aspect information, shaded overlay, or remotely-sensed data (eg. satellite imagery) data.

The grid and vector data may be displayed independently, but more importantly they may also be displayed together using the program. The user is able to derive considerable benefits from this integrated display:

Using a digitising table the user is able to move around and edit matrix values. Editing facilities within ROVER offer the option of editing a single data value, a line of values or all values within a defined area. The grid data may be edited with reference to any overlaid vector information.

ROVER provides a display link between Laser-Scan programs that manipulate and display grid and vector datasets. The Laser-Scan programs that either generate or utilise digital terrain matrices (See the SPS for Packages DTMCREATE, MATRIX and TVES) are of particular relevance, along with Laser-Scan's vector cartographic editor (LITES2) and plotting program (FPP). The modules I2GRID (vector to raster conversion) and VECTORISE (raster to vector conversion) are also significant for preparing data for display within ROVER.

The main features of ROVER are:

Raster Display Facilities:

Vector Display Facilities: Raster Edit Faciltiies:


SLOPES generates slope or aspect information from elevation data held in the form of a grid based DTM. The module may also be used to produce a shaded overlay. The derived information may be displayed as a classified image on a suitable colour graphics device, or may be output to a disk grid file for subsequent manipulation or fast display using modules within the TVES package.

The information derived from the elevation data on slope and aspect represents a valuable end product in itself, but more importantly may be an input into a Geographic Information System (GIS).

SLOPES features are:


The module VECTORISE allows grid based data (raster) to be converted into a vector IFF representation. Lines generated from the raster image by VECTORISE are the boundaries between areas in the grid file whose pixel values fall into user defined ranges. The input grid file may contain a variety of geographic information ranging from elevation or slope data to remotely-sensed satellite imagery.

The main features of VECTORISE are: