Bitmap images and vector graphics - definition of terms and differences

TaskVisualization + Paint + As-completed Drawings

Using Allplan, you can create and process two completely different types of data, vectors and pixels. At first glance, the result may often be the same - however, the differences between these two forms of data processing are significant.

Terms: vector data

CAD systems that aim to produce precise drawings work with geometry-oriented CAD data. The elements in a CAD drawing are saved as vectors. These vectors serve to define the elements and allow them to be identified as such.

A straight line, for example, is defined by its start point, end point and the direction; a circle consists of a center point, a radius and an angle. Complex geometric entities such as splines are approximated using mathematical formulas.

A CAD drawing thus consists of a series of geometric values entered via the keyboard or using the mouse. These values are exact values and are based on the defined coordinate system.

Vector data are "intelligent": When you resize vectors or zoom in on details, the vectors themselves are still mathematically precise. The representation adapts to different scales and sizes. Therefore, there is no loss of quality even when you print out vectors as large-format drawings.

Terms: bitmap images

Bitmap images consist of a series of pixels. Information on the position and color of every pixel within a dot grid is stored.

Together, the pixels form an image somewhat similar to a photograph in a newspaper (these are also merely a series of dots). The nearer you are to the image, the more visible the individual dots. The finer the grid of dots, the better the resolution.

When you render an image, you cannot enlarge it without suffering loss of quality. This is because only the pixels themselves are enlarged, thus leading to deterioration in the quality of the picture - even with small pictures: The image appears coarse, sloping lines look like steps and even smooth transitions from one color to another increase in contrast.

Bitmap images can be rendered using different resolutions. The higher the resolution of the bitmap image, the better the quality. However, the amount of data generated also increases significantly and the operation can take much longer as a result. When rendering a bitmap image, keep the printout format in mind and set an appropriate resolution.

Vector data and bitmap images in Allplan

Elements you create in Allplan are generally saved as vector data; the exception is the bitmap images of the Visualization task or scanned drawings of the As-completed Drawing task area (Design task):

• The tools in the Shadow and Paint task areas (Design task) create vector data, which you can manipulate at will without losing quality.
• The tools in the Surfaces, Light and Camera task areas create and process pixel data.
• The As-completed Drawing task area is an exception: hybrid data processing (i.e. both). This means that you can resize, move the bitmap data (= pixel data) in a scanned image as if the data were vector data. The scanned image's bitmap data behave like vector data. However, with high-factor enlargements, aliasing will become more evident.