Skip to content

Chapter 9 - Bitmaps

Note

This chapter describes the features of the CadnaA option BMP.

By the CadnaA option BMP bitmap files having various data formats can be imported and transformed (see Import Bitmap).

Bitmaps are the most common data format for pictures, suchas photos or drawings.

The representation of bitmaps depends on their resolution, i.e. from the number of pixels per unit length (DPI, dots per inch). When transforming the scale of bitmaps on the screen or when printing using a low resolution may result in a loss of details.

Most commonly, the option BMP is used to import and transform scanned drawings, such as site maps or maps form a land register. They serve as a background image to enter sources, receiver points and other objects. Further, pictures and orthophotos can be imported as well. The maximum number of images that can be imported depends on the available memory and the resolution in DPI of the images.

Loading of stored Bitmap Files

There are several ways to load referenced (stored) bitmap files. The priority order of loading is as follows:

  1. Search in the directory specified on dialog Bitmap, in line „File“.

  2. Search in the directory specified in the file CADNAA.INI. Regarding the location of the file CADNAA.INI see Installing CadnaA, INI-files in the manual "Introduction to CadnaA".To this end, write the following link into a line in section [Main] of the INI file:BMPROOT = For example: BMPROOT=C:\temp\bitmaps

  3. Search in the directory where the CadnaA project file (file extension *.cna) is stored.

  4. Search in the CadnaA installation directory (location of the file cna64.exe).

Using relative File Paths

Besides absolute file paths also relative file paths can be used. This requires that the bitmap is not selected via the file selector symbol on dialog Bitmap, but to specify the path in column „File“ of the Bitmap table on the Tables|Other Objects menu.

Examples of relative paths in table Bitmap

The naming rules for the file path corresponds to those established for WINDOWS systems.

Access to the relative path:

"..\data\bitmap1.bmp"

starting from "C:\private\texts" is interpreted as:

"C:\private\texts..\data\bitmap1.bmp"

The string ".." means a change to the parent directory. This is the resolve simplified pathname is:

"C:\private\data\bitmap1.bmp"

Furthermore, within this example the path:

".\bitmap2.bmp"

calls for the path:

"C:\private\texts\bitmap2.bmp"

as the point „.“ stands for the current directory.

Of course this can be simplified by (i.e. omitting the leading string „.\“):

"bitmap2.bmp"

Note

The priority order (No.s 2 to 4) also applies when loading files having relative file paths. It is searched at these locations just using the filename, not taking into account the stated path.