TM image interpretation
The TM image interpretation of remote sensing data is carried out from different perspectives depending on the research objective .
description
With automatic classification , image points from primary data are bundled as so-called clusters based on the various degrees of reflection .
The supervised automatic classification also works with clusters that are formed by humans. In training areas , pixels are summarized as secondary data , the importance of which people are sure of, for example only linden trees grow in a city park, so these degrees of reflection of the pixels are defined as linden trees. The advantage lies in the detection of the same vegetation with inconsistent degrees of reflection, which can result from inhomogeneous health or growth conditions.
The visual interpretation is based on primary data and secondary data according to the following criteria:
- Geological evaluation
- Reliefs
- Waters
- Volcanoes
- erosion
- Removal
- Evaluation of the vegetation
- Plant species
- Field crops
- Forest cover
- Land use
- Settlement area
- Commercial space
- Industry
- Leisure facilities
- Traffic routes
For the different objectives, the different grayscale images of the individual spectral channels of a recording surface are combined to form a three-color RGB image.
Summary of the most common channel combinations of the Thematic Mapper :
| R. | G | B. | Interpretation application |
|---|---|---|---|
| 3 | 2 | 1 | natural sequence = real color display |
| 4th | 3 | 2 | CIR false color image (comparison with MSS data possible) |
| 5 | 4th | 3 | Vegetation & Land Use |
| 7th | 4th | 1 | geology |
| 5 | 7th | 2 | geomorphology |
Examples
Visual image interpretation of Hamburg
The following picture shows the Hanseatic City of Hamburg and its surroundings, as well as selected enlargements from the remote sensing data of the Thematic Mapper from the Landsat 4-5 TM satellite.
The section shows the channels RGB = 321. This representation corresponds to an aerial photograph and is therefore referred to as true color representation. The visual interpretation is an important part of the image interpretation.
The Elbe with its arms Norder- and Süderelbe, as well as the tributaries Alster (lake in the city center) and Bille , are clearly visible. The almost white areas near the Elbe are undeveloped sand deposits, some of which belong to the Elbe beach or to rinsing areas.
The 6 enlarged sections at the edges show known locations that are to the right of the numbers on the overview photo.
Red numbers
No.1 Hamburg city park with city park lake - dark square southeast in front of the light green lawn. The planetarium is at the end of the path through the city park forest in the north-western corner.
No.2 Elbe at the St. Pauli Landungsbrücken. On the south side of the river are the 2 large floating docks of the Blohm & Voss shipyard. On the north side you can see the copper-covered roof of the old Elbe tunnel with a light green spot.
No.3 The Billebad outdoor pool. The pools are characterized by a light light blue. The dark area south of the bath belongs to the Bille .
No.4 tennis courts and sports fields on Rothenbaum
No.5 construction site at the Hamburg-Stellingen junction . Route of the A7 from south to north, junction of the A 23 to the west.
No. 6 The so-called Inner Alster in the heart of Hamburg City. In the southwest of the Jungfernstieg , in the northwest, the copper-covered roof of the hotel "Vier Jahreszeiten" is conspicuous as bright green pixels. To the north are road and railway bridges, as well as the confluence of the Outer Alster .
Blue numbers
No.7 The town of Pinneberg in Schleswig-Holstein
No.8 The town of Wedel in Schleswig-Holstein
No. 9 The town of Uetersen in Schleswig-Holstein
No.10 The town of Elmshorn in Schleswig-Holstein
Green numbers
No.11 International Airport Hamburg-Fuhlsbüttel with 2 crossing runways.
No.12 company airport Hamburg-Finkenwerder with one runway. Below the number is the shallow water area of the Mühlenberger Loch nature reserve . In 2001, the filling of this water area began. There are now new halls for Airbus production .
Temporal changes
The series of images show comparative images of the satellites LANDSAT 1-3 from 1976 with a resolution of 76 m and LANDSAT 4-5 from 1991 with 30 m resolution in infrared false-color representation from the greater Hamburg area.
The comparison picture shows the Hamburg-Stellingen industrial park. The marshalling yard (top right) has not changed, as has the course of the A 7 (gray line). However, the adjacent commercial area, recognizable by its light blue color, has become significantly larger, while the number of allotments (light red) has significantly decreased.
The comparative photo shows part of the runway at the Airbus company airport in Hamburg-Finkenwerder. The filling of a harbor basin (1976 black) at the end of the runway (1991 light turquoise) is clearly visible.
The comparison picture shows an oxbow lake of the Elbe on the north bank of the Haseldorfer Marsch . While the construction of a storm surge protection dike (light red line) was still ongoing in 1976, the 1991 photo clearly shows the separation of the oxbow lake by the dike .
Visual interpretation of images of Krakow
The image above shows three identical data extracts from the Polish city of Krakow, which were compiled from the remote sensing data of the Thematic Mapper by the Landsat 4-5 TM satellite for image interpretation .
The first section shows the channels RGB = 321. This representation corresponds to an aerial photograph and is therefore referred to as true color representation . The course of the Vistula can be seen clearly here, as well as the bridges over the river. Light orange areas are tennis courts. In the city center, the market square is clearly recognizable as a light area. The vegetation is difficult or impossible to see.
The second section shows a combination of the channels RGB = 543. The tree-lined green belt around the city center is very clearly visible here. You can also make out some avenues and other green spaces. Differences between individual groups of trees (genera) are also possible in the original image. Even wider streets stand out clearly from their surroundings - bottom right. The bridges over the Vistula are hardly recognizable.
The third section shows the thermal channel 6 in false color representation. The reduced pixel resolution of 120 m × 120 m does not reveal any smaller structures. However, the differences in heat become visible. Where the green belt is wide (compare section 2) it is colder than on the built-up area in the city center. The market square, paved with light granite (compare section 1) is a little cooler than the roofs of the city center. The river also appears cold, although bridges are indirectly recognizable due to the increased heat radiation.