General Principles

Novapoint uses Quadri as database. Quadri is a computer program, which stores the topographical information and can be retrieved at any instant in the form of graphics or printouts. Quadri is a Latin word, which means, “the place where four roads meet”. The name was selected as the program links the four planning elements:

• Map production
• Geo-related information (LIS/GIS)
• Terrain modelling
• CAD/Planning

In practice, Quadri means that geographical and design data can be stored in one database, and can subsequently be used either for information purposes, or directly in planning activities without the need for conversion via ASCII files. Quadri represents topography/terrain in digital form, as a model of the terrain, and thus it is also known as terrain model or digital terrain model.

In this manual/help file, the terms, terrain model, digital terrain model, or Quadri, refers database.

To certain extent, terrain model is a standalone application, which is included as an integrated unit within a larger planning system for area and transport planning. The program has been developed to allow simple evaluation of several alternative designs in relation to terrain cutting and earthworks balance.

When a new database is created, it will be empty. Data is to be imported to the terrain model. Data is termed as primary data (survey data, digital maps, etc.) or secondary data (grid model, triangle model, contour model) depending on the source. Program generates the secondary data from the primary data, which is termed as terrain modelling. One of the main features of terrain model is that it interpolates heights by the linear method, between two successive points on a straight-line.

Primary data in various formats can be imported to the database. Detailed descriptions of various formats, which can be imported to the database, are explained in the preceding topics of the section 'Terrain Model'.

There are number of survey methods, which may be used to obtain primary data for the terrain model. The methods we recognize are, field surveys using total station instrument/electronic field book, digital maps, digital mapping data from stereoscopes, and keying in individual points. All of these methods can be used in one and the same terrain model. In this way, the most accurate data can be used in those areas of the project, which are most important and demand higher accuracy. Other modest data such as digital maps or stereoscopes can be used in areas, which do not demand great accuracy. More details on primary data are explained in the topic 'Primary data'.

Importing data from AutoCAD drawing file (2D or 3D) to database is also possible.

When data is imported to the terrain model, it is organized in Groups and Feature codes.

Groups are used for rough geographical sorting (organization) and quality grading of data. For example, group numbers will be used to differentiate between geographical areas, to differentiate contours from situation charts, to differentiate terrain surface from terrain cuttings or geological layers, etc. Priorities can be assigned for Groups, and during executing calculations, program will access/read the data in the database as per the assigned priorities. For e.g. if digital maps and total station instrument measurements exist for the same area, they should be stored under different Groups and appropriate priorities are to be assigned. More over, groups, which are not to be considered by the program in calculations, can be turned passive. Groups in terrain model are identified with Group numbers. Every time a group is created, group number is to be defined by the user. A group number must always be a number greater than zero. This will be used to group or “roughly sort” the terrain data.

Feature codes are used for sorting/identifying data types, e.g. contours, road edges, railways, streams, power lines, etc. Feature code is a numeric code, assigned to different types of data, which we come across during surveying. All such feature codes put together forms a feature code register. Feature code register is national standard and different nations may have their own standard feature code register. Quadri is equipped with a bank of feature code registers (feature code library). By default, database will follow the SOSI feature code register, which can be changed to desired pre-defined/user-defined feature code register. Users can also define their own feature code register.

Feature codes are normally assigned during surveying when data is being logged, and are contained in the data file. When such data files are imported into the database the feature codes are also brought in along the data (feature code register of database and the data file being same). Quadri is equipped with feature code conversion, if the feature codes are to be converted from one standard register to the other during import. This implies that primary data in various formats and different feature code registers can be imported to Quadri.

SOSI feature code register is Norwegian Mapping Authority's standard, which makes the software very flexible and allows detailed characteristics to be stored in addition to co-ordinates and feature codes. We recommend that the user use the SOSI feature standard if he does not have his own standard feature code register.

Feature code library also contains information on how the different features are to be represented, linetype, color, symbol, pen number, smoothing, etc.

As in groups, feature codes can also be turned active or passive depending on the situation. Participation of feature codes of the active groups, in calculations can be controlled with this active/passive option. Deliberate use of group numbers and feature codes allows close control of the terrain model.

Database searches can be carried out on parameters such as, geographical areas, types, object names, groups, or layers.

User will be able to freely define data structure and data organization in terrain model. For example, one group might contain mapping data, a second the horizontal geometry, a third a chart of power lines, etc.

In a planning task, it is often desirable to log information other than the terrain. Quadri is capable to do this. Quadri can store all information pertaining to the planning process. The information must be linked to co-ordinates but not necessarily defined by height. An example of this might be text from a SOSI file linked to an object. The model can, at any time, be supplemented with new elements, as planning progresses.

At the time of data import, means are available for limiting data. The purpose of this is to reduce the amount of data in the database, thereby increasing processing speed.

Another method of limiting data during import is to employ filtering. Filtering will filter any unnecessary data from import data, which may not be essential.

The sub surfaces details can be define using the routine 'Define Sub Surface Layers'. Data related to terrain sub surfaces can also be imported to the database as separate group.

Sub-surface heights can be defined either as relative heights or absolute heights. In certain cases it will be practical to use relative heights instead of absolute heights, for example, for drilling depths as opposed to absolute bedrock depths. In that case, the height is assumed to be relative to the terrain surface.

The terrain can be described as an unlimited number of layers/stratum in the ground. Several group numbers can constitute a layer.

Levels are used to differentiate between several physical layers in the terrain model. Level is numeric value with positive or negative sign. Negative prefix indicates, sub-surface layers. Numeric value '0' indicate terrain surface. Positive prefix indicate proposed, planned, designed surface (projected road surfaces etc.). Levels are also used to assign priorities among sub-surface data, e.g. designed surface level higher than existing terrain surface.

Data can be exported from database to various file formats. Detailed description of various file formats for exporting data are explained in the preceding topics of the section 'Terrain Model'. Data can also be transferred to AutoCAD drawing files (2D or 3D).

Areas in which Terrain Model may be applied are as follows:

1. Planning residential areas, industrial estates.
2. Planning roads, railways, airports and terminal buildings.
3. Planning dams, hydro-graphical surveys.
4. Landscaping of all kinds.
5. Planning open-cast mining operations.
6. Modelling raw materials deposits and plans for extraction.
7. Modelling large concrete structures.
8. Construction of contour maps from total station instrument measurements.
9. Analysis of the visual impact of structures.

The main characteristics of terrain model are as follows:

1. Several alternative methods for data surveying.
2. The same model can contain information from a wide variety of surveying instruments.
3. Can be used for projects, which demand great accuracy, which is not always possible with digital surface modelling systems.
4. Can operate as an information bank for surveyed or digitized mapping data irrespective of topography. E.g. property boundaries, roads, houses, posts, manholes, pipelines, etc.
5. Flexible graphics module in which you may select group number, type, scale, legend, symbols, colors, shading, etc.
6. Both primary data modelling and grid modelling.
7. Simple to use.
8. Adapted for practical applications, especially in relation to projected highways.
9. CAD links.

For further details refer the topic Primary Data.

For further details refer the topic Working Practices.

For further details refer the topic Terrain Modelling.

For further details refer the topic Survey Methodology.