Setting the resolution of bitmaps

Creating bitmaps is equivalent to holding a camera in your hands. In particular, this applies to the generation of 3D models in the Animation module, which can be compared to the process of snapping pictures. The saving of an animated image is similar to developing photographs. Reality is not displayed to scale.

When you use Render to calculate the front of a 3D box (each side represents 1m) with a render size of 800x501 pixels and display the image on screen or print it, you can no longer find out how long the sides of this box are without knowing the real size of the box.

The same applies to photos. The actual size can only be determined if a unit of measurement was visible on the box. Transferring to scale requires references: a conversion unit, i.e. dpi (dots per inch). The output device must always be taken into consideration when you select this conversion unit.

Resolution of bitmaps and print quality

To obtain a good print quality of bitmaps, the resolution is a decisive criteria, i.e. the number of pixels in a specific section. Modern inkjet printers usually print at a resolution of 300 dpi, that is 300 pixels per inch. In other words, about 12 pixels per millimeter. Approximately 3,240 x 2,340 pixels are necessary to produce a bitmap with a resolution of 300 dpi in the A4 size (approximately 270 x 195 mm; less margin). Enlarging the area considerably increases the number of pixels and disk space required.

Note: Selecting a resolution that is far too high for the printer will not improve the quality!

Examples of a conversion with 300 dpi

Format	Size in mm	Number of pixels	File size
Din A4	approx. 270x195	3,240x2,340	21.6 MB
DIN A3	approx. 400x270	4,800x3,240	44.4 MB
DIN A2	approx. 570x400	6,840x4,800	93.9 MB
DIN A1	approx. 820x570	9,840x6,840	192.6 MB
DIN A0	approx. 1,160x820	13,920x9,840	391.9 MB

Calculating the resolution

When you save the contents of the Animation window as a bitmap (= screenshot) in the Animation module, the number of pixels is calculated from the size of the window and the resolution of which the monitor is capable. In conjunction with a 24" monitor (16:10), which is recommended for CAD programs, and the animation window set to full screen, this results in approximately 1,916x1,148 pixels.

A printer resolution of 300 dpi leads to the following values:

Number of pixels	Size in mm	File size
1,916x1,148	approx. 160x96	20.8 MB

To achieve a higher quality (e.g. 600 dpi) in printouts, you can reduce the size of the image by half, to 80x48 mm in our example.

If you enlarge the image although a higher number of pixels is not available, the resolution deteriorates. For example: In the case of a printout of 50 cm, 1916 pixels result in:
(1916/50) = 38.32 pixels per cm = (38.32*2.5) = 95.8 pixels per inch,
which corresponds to a resolution of 96 dpi.

Rendering with a high resolution

In the Animation module, you can use the Redner tool to configure the system to calculate more pixels. The render size has to be changed accordingly. The maximum render size is 10,000 x 10,000 pixels. The higher the number of pixels, the longer the computing process. To be on the safe side, however, it is advisable to settle for a compromise between number of pixels and computing power in order to avoid pushing the hardware to its limits.

Additional tips:

Producing high-resolution pixel images