TECHNICAL NOTE OF DIGITAL REPRODUCTION OF CARTOGRAPHIC MAPS

Raster format

• Raster Images of Cartographic Maps, of any scale and any projection.
• Toponymic themes in vector format for Geographic Information Systems
• Data are ready to use and can be integrated into any GIS and any CAD or image system.

Production of raster images being a facsimile of the original map. The raster files being delivered are calibrated. Data are organized in the projection that the client will use. This means that :

• Xs and Ys of the raster file will corrrespond to the northings and eastings chosen to be displayed. For instance, in UTM projection, each line of raster file will follow a paralel, and each column will follow the false northing of the UTM grid. There will not be any drift from this specification.
• Each pixel in the raster file has a perfect square shape.
  
• Resolution :
  We propose resolutions to the customer needs. - for instance 1:25 000 : 254 dpi resolution and 2,5 meters pace or 158 dpi resolution and 4 meters pace. This resolution defines the number of data.
  
• Pixel - pace :
  - in DMS projection and according to the different utilisations, pixels can have or not a same X and Y pace.
  - in conical projection (Lambert) or cylindrical (UTM), pixels have a square form and a same pace concerning all   files.
• Palette :
  The color number is minimized in order to get a precise information with a minimum of data. This can be of 32K colors without frame to 16 framed colors. We can also import your palette or provide some files with a few color selection.

Due to these processes data are ready to use and need no further transformations. Raster files Geo 3D include all of the geodetic informations required.

Vector format

Thematic layers are supplied in vector format. The themes are extracted by a semi-automatic vectorization process. The precision and roughness of the vectors are tunable depending on the customer's needs.

Technology

For the vectorization process, we use image recognition technology and neural networks. The main tool, GeoImage detects automatically the colors of the selected themes on the map. It monitors the operator to tag the forms encountered. For the raster files, the maps are scanned, coordinates are attached to the known points on the map. Then the map is projected according to the user's need. Pixels are calibrated for the best ratio data size vs. readability.

The result is a facsimile of the original map. Nothing has been redrawn by hand. The result is much more precise than any other technique.

Accuracy

As mentionned, due to the GeoImage features, the result is very similar to the original map. The precision is always better than the graphic accuracy of the paper map.

For instance on a 1:100,000 map, TEIS accuracy will be 200µ (20 meters), although graphic accuracy is 400µ (40 meters).

The XY precision applies for adjacent maps as well. The connection falls within 1 or 2 pixels.

Geographic coordinates

The data are delivered in any of the projections or references of the map. It can be UTM, DMS, Lambert, gauss or any exotic system or Datum as long as the values are visible on (or inferable from) the map.

Standards

We respect ISO, and Digest standards.

Formats

The raster files are supplied in standard formats. When the format includes a header, all of the relevant informations to display the map are available in the file. Namely, coordinates of the corners, pace of the pixels, Look Up Tables. This is the case for, IGN France, Intergraph Raster File. Due to our projection process transformation matrix is always a unit matrix.

TEIS produces data in standard image format such as TIFF, TARGA and many others. In these cases geodetic informations are supplied on seperate files.

Paper size converted to raster files will depend exclusively on the user application. Multiple maps can be joined into a single file, or data can be split into as many tiles as the user needs. Tiles will join with no gaps and no overlay (unless one profile redundancy is required by the format).

The vector files are supplied in DXF format.

Medium

We support standards media such as diskettes, DAT, DC6xxx, DC2xxx and CD-ROM. Data can be coded for DOS.

COMMERCIAL NOTE

- List of products already existing in the the catalog are available with technical notes and prices.
- For products not available in the catalog, we realize an estimate for prices.

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