Scale and resolution of Remote Sensing Images

Someone asked me the day before yesterday. I don't know yet. I saw it on the Forum and added it to my favorites. Haha

Scale and resolution of Remote Sensing Images

The image resolution rate is an important indicator for determining the image accuracy. The image accuracy must meet the image recognition capability and accuracy requirements of the corresponding scale map update, and the map update cost must also be taken into account. Redundant resolutions increase the cost of purchasing weixing images and increase the burden of internal processing. If the resolution does not meet certain requirements, small features cannot be interpreted, and the precision of image control points cannot be guaranteed, the accuracy of the graph cannot be met. When selecting an appropriate resolution rate, consider the most unfavorable production conditions.

1. Requirements of aerial photography and Measurement on Images
The practice of aerial photography measurement can be used for reference to the selection of satellite images and ing scales. This is because they are similar to the ing principle, and aerial photography has a large amount of practical experience and experimental data, which is very mature.
Aerial photography does not directly provide the requirements for image resolution, but can be inferred by the requirements on the camera lens resolution and the photography scale. The resolution of the aerial photography lens represents the minimum width of the lines that can be distinguished on the image after aerial photography (the Resolution of the soft film and photo paper is not considered here ). In the aerial photography specification (GB/T 15661-1995), it is stipulated that the effective use of the lens resolution within the area of the aerial photography "no less than 25 lines per millimeter ". Based on the objective lens resolution and photography scale, the corresponding ground resolution D on the aerial photography image can be estimated, that is, D = m/R. (M indicates the photography scale denominator, and r indicates the lens resolution .) According to the "Choice of aerial photography scale" in the aerial photography specification and the above formula, see table (1)
Map scale aerial photography scale image ground resolution (m)
To ~ 000 0.4 ~ 0.8
, 000, 000 ~ 000 0.8 ~ 1.6
5000 ~ 1: 60 000 1.0 ~ 2.4
, 000, 000 ~ 1: 80 000 1.4 ~ 3.2

The preceding table can be used as a reference for selecting satellite image resolutions. By the way, we can see from the table that although the larger the scale, the higher the image resolution, the two are not linearly proportional, but non-linear.

2. Satellite image resolution Selection
In addition to the image resolution requirements of different scale maps, the resolution requirements of satellite images are also considered. Because satellite photography is different from aerial photography, its photography height (that is, the photography scale) is fixed.
The resolutions of several commercial satellite images are listed below. Table (2)
Satellite QuickBird-2 IKONOS-2 spot-5 Spot-4 Landsat-7
Maximum resolution (m) 0.61 1 2.5 10 15
For comparison tables (1) and (2), I personally think that for the current stable sources of satellite images ~ The following resolution options can be considered for the 000 basic surveying and mapping update test. Table (3)
Ing scale satellite image (resolution)
~ 000 Quickbird (0.61 m)
IKONOS-2 (1 m)
000 QuickBird-2 (0.61 m)
IKONOS-2 (1 m)
Spot-5 (2.5 m)
000 spot-5 (2.5 m)
If a region with an old version of topographic map has a reference point with sufficient density (which can be consistent with the same position point on the weipin) for range control, when the topographic map is updated quickly (for repair and retest), you can consider relaxing the resolution requirements, for example, using a 2.5 m resolution patch for local repair and retest of A 000 topographic map, use a 10 m resolution patch for local repair and retest the 000 topographic map.

Supplement:

Million dem-M spatial resolution;
Dem-M spatial resolution;
Dem-25 m spatial resolution;
Dem-5 MB spatial resolution.