Keywords: Resolution, Calibration
Abstract APS (Advanced Photographic System) is a new camera format recently introduced to the market. The APS formatted camera's photogrammetric potential is tested in this study with practical experiments. The photographic resolution is first evaluated with the USAF optical test pattern-resolving power chart. Then a test field is used for the evaluation of the metric properties. After the photographic development, the photographs are scanned and the image coordinates are then measured in a digital environment. In comparison to Wild P32 metric camera, significantly larger distortions were found with the tested Kodak Advantix 2100 Auto camera.
1. Introduction
The Advanced Photographic System (APS) is a new commercial photographic system developed by the alliance of Cannon, Kodak, Fuji, Minolta, and Nikon. The objective of APS development is to provide a more reliable commercial photographic system with better quality. Although APS is not expected to replace the commonly used 135 format camera completely, it is hoped that the APS format camera will eventually share a significant portion of the market.
The effective exposure area of traditional 135 format film is 24mm×36mm. While the film size of APS is smaller, 16.7mm×30.2mm, the image quality is not reduced. A newly developed film technique made this possible. With smaller film size, cameras can be made more compact. Usually the APS camera is 20% smaller than its 135 format counterpart. This may not be an advantage for close-range photogrammetric applications, because the photo scale is smaller for the same object distance and focal length.
There are three photo formats available in the APS system. As listed in Table 1, each photo format has a different aspect ratio. Accordingly, each photo format has different magnification scales. In this study, H format is selected.
Table 1: APS Photo Format Specification
| Name |
Aspect Ratio |
Format (mm) |
Magnification |
| C |
2:3 |
4×6 (102×152) |
6.1 |
| H |
9:16 |
4×7 (102×178) |
6.1 |
| P |
1:3 |
4×12 (102×305) |
10.1 |
A low-end APS camera, Kodak Advantix 2100 AUTO, is used in this study. The focal length is 25 mm with maximum aperture f/5.4. Because the APS film is designed that it will not to be accessed by the user, the photo coordinate measurements are performed with the developed photo, not the film.
2. The Resolution
LPM (lines per millimeter) is frequently applied for measuring the resolution of an imaging system. In this study, a printed standard chart is posted onto a vertical wall as the reference for evaluation. In this chart, there are groups of bars with different widths and four different colors, namely, black, red, blue, and yellow. The developed paper prints are scanned with 300, 600, 1000, and 1500dpi with a desktop flatbed scanner. The evaluation is performed on the screen of a personal computer. When the three lines cannot be differentiated, the LPM number is obtained from the look-up table printed on the reference chart. Then, the largest LPM value among all groups is taken to compute the LPM value of the photo.
LPM photo = LPM chart×(D-f0)/f0 (4-1)
Where D is the distance between the camera and the chart; f
0 is the focal length of the camera.
Table 2: The Resolution of Kodak Advantix 2100 AUTO I (300dpi)
| Distance (cm) |
LPM chart |
LPM photo |
Photo Scale |
| 100 |
0.891 |
34.7 |
1:6.20 |
| 120 |
0.707 |
33.2 |
1:7.37 |
| 150 |
0.629 |
37.1 |
1:9.27 |
| 180 |
0.500 |
35.5 |
1:11.11 |
| 240 |
0.354 |
33.6 |
1:14.51 |
Table 3: The Resolution of Kodak Advantix 2100 AUTO II (600dpi)
| Distance (cm) |
LPM chart |
LPM photo |
Photo Scale |
| 100 |
1.000 |
39.0 |
1:6.20 |
| 120 |
0.794 |
37.3 |
1:7.37 |
| 150 |
0.707 |
41.7 |
1:9.27 |
| 180 |
0.561 |
39.8 |
1:11.11 |
| 240 |
0.397 |
37.7 |
1:14.51 |
Table 4: The Resolution of Kodak Advantix 2100 AUTO III (1000dpi)
| Distance (cm) |
LPM chart |
LPM photo |
Photo Scale |
| 100 |
1.000 |
39.0 |
1:6.20 |
| 120 |
0.891 |
41.9 |
1:7.37 |
| 150 |
0.707 |
41.7 |
1:9.27 |
| 180 |
0.629 |
44.7 |
1:11.11 |
| 240 |
0.445 |
42.3 |
1:14.51 |
Table 5: The Resolution of Kodak Advantix 2100 AUTO IV (1500dpi)
| Distance (cm) |
LPM chart |
LPM photo |
Photo Scale |
| 100 |
1.000 |
39.0 |
1:6.20 |
| 120 |
0.891 |
41.9 |
1:7.37 |
| 150 |
0.707 |
41.7 |
1:9.27 |
| 180 |
0.629 |
44.7 |
1:11.11 |
| 240 |
0.445 |
42.3 |
1:14.51 |
From tables 2, 3, 4, and 5, it is observed that there are differences among the photos taken with different object distances, while the scanning resolution is the same. However, if the number is normalized with photo scale, the resolution is about the same. It is also observed that the LPM improves with higher scanning resolution. But, the LPM remains the same after certain scanning resolution. That is, after certain scanning resolutions, the resolution of the photo itself becomes the governing factor.
