(1) Selection of Remote Sensing Information Sources (Table 8-3)

The remote sensing guide map adopts TM digital images obtained by Landsat-5 Landsat TM thematic plotter launched by NASA on March 1984 and March 19981October 3 (Dongjiang Reservoir). And the true color aerial photograph (Yuelu Mountain) acquired by Canadian Double Otter Aircraft 1986+ 10/0, in which the TM image resolution is 30 m, the band is composed of TM5, TM4 and TM3 in red, green and blue respectively, and the aerial photograph scale is1:10000.

(B) the choice of key tourist areas (spots)

The key tourist areas (spots) are Dongjiang Lake area and Yuelu Mountain area, which represent the tourist landscape characteristics of lake area and urban mountain type respectively, and have their own characteristics in remote sensing images, which are very representative.

(3) Collection and arrangement of tourism materials

Collect relevant information of scenic spots in an all-round way, including topographic maps, maps, geographical base maps, tourist sketches and various achievement reports of tourist areas at various scales, and finally complete the comprehensive analysis of information through field investigation and verification of various scenic spots (points).

(four) the software and hardware environment for the compilation of the guide map

(1) Software environment: Windows98 operating system, ENVI remote sensing image processing system, MAPGIS geographic information mapping system, PHOTOSHOP plane image processing system.

(2) Hardware environment: the host is configured as CPU-P Ⅲ 800, RAD-256M, IDEDISK-80G, AVG-17 "; The peripherals are Ls8000(A0) scanner (800DPI), (A4) color scanner (1200DPI), HP3500 color inkjet plotter (600DPI), external burner, etc.

(5) image processing

(1) Image synthesis: In order to meet the needs of extracting tourism information, the three primary colors of R, G and B are given by TM5, TM4 and TM3 in Dongjiang Lake area (TM 122-42 scenic spot) for false color synthesis, and the surface reflected by the synthesized image is close to true color.

(2) Geometric correction: In image processing, the orthographic center projection of the system is used for correction first, and then the geographic coordinates are corrected with the geographic base map, which greatly improves the accuracy of the image.

(3) Image stitching: Because there are 20 true-color aerial photographs of four lines in Yuelu Mountain area, the scenic spot (work area) is not in one aerial photograph, so it is necessary to stitch the images. Mosaic processing is completed in the 3.0 version of the new remote sensing image processing software ENVI system.

8.4.2 Interpretation and production of remote sensing images of key tourist areas (spots)

(A) image interpretation

(1) Establishment of interpretation marks: In the process of interpretation, the interpretation marks used include shape, color, water system, landform, shadow pattern, soil vegetation, human environment, etc. Among them, the most important thing is the shape and color.

(2) Interpretation method: This time, visual interpretation, optical enhancement processing and computer digital image processing are mainly used as auxiliary methods.

Table 8-3 Summary of Main Remote Sensing Information Sources in Hunan Province

(3) Interpretation map making includes ① tourism information extraction: interpreting linear features (lanes, sidewalks), scenic spots and scenic spots distribution on synthetic images; (2) Transparent film production: The interpreted information is drawn on the transparent film (inked) and completely nested with the base map image.

(2) the production of the result map

(1) Making remote sensing interpretation map: scan the film made by interpretation, vectorize it in the graphic editing of MAPGIS software, and edit it into remote sensing interpretation vector map.

(2) Registration of interpretation map and remote sensing image: the edited vector map is corrected, rotated and stretched to make it completely registered with the satellite image, and then the two are combined into a remote sensing guide map by PHOTOSHOP.

(3) Modification of the guide map: In order to make the result map beautiful and harmonious, it is necessary to modify, label and change the color of the nested images, which are all done in the PHOTOSHOP image processing system.

(4) Output of results: The finished results are printed and output by HP750 color inkjet plotter.

(C) the characteristics of the guide map

The guide map made by satellite remote sensing images can not only reflect the morphological characteristics and spatial distribution of various tourist landscapes, but also show the relationship with surrounding environmental groups. Compared with the traditional tourist map, this map is clear and easy to read, colorful, richer in content and more expressive. In particular, large-scale images have the advantages of high resolution, strong three-dimensional sense, intuitive and real surface landscape, which gives people a wonderful feeling of standing on a satellite overlooking the earth, which can be fully recognized and accepted by non-professionals.

(four) the remote sensing guide map and description of key tourist areas (spots)

(1) Dongjiang Lake Scenic Area: This area is located at the southern end of Luo Xiao, on the upper reaches of Leishui River, only16km away from Zixing City, the "south gate" of Hunan Province. It is a bright pearl on the golden tourist route of Hunan, Guangdong and Jiangxi, the best tourist destination and the top ten tourist attractions in Hunan Province.

The landscape of Dongjiang Lake is an artificial mountain lake. On the TM image, it extends along the river valley, forming a long, narrow and curved blue lake. The mountains on both sides of the river are green and green, and the mountains are yellow and green. The linear image of the ridge line is clear. It belongs to erosion structure and alpine landform. The basement is dominated by metamorphic rocks with hard lithology. The light blue tone in the west, mainly exposed carbonate rocks and clastic rocks, belongs to karst hilly landform, and the images are quite different.

Dongjiang Lake Tourist Area has modern tourism characteristics of fame, uniqueness, novelty, danger and strangeness. Dongjiang Dam is located in the upper reaches of Zixing City at 1 1 km, with a dam height of157 m. It is a concrete hyperbolic arch dam with magnificent momentum, ranking first in China and second among similar dams in the world, which is quite ornamental. Dongjiang Lake is also a national key forest area with a vegetation coverage rate of 90.8%. Scenic spots mainly include the gatehouse, the rime Jiang Xiaodong River, Dongjiang Dam, Hougushan Waterfall, Doulu Lingyan, temples and caves, Cuiyongxia, orchard scenery, Dongjiang rafting, holiday islands and other scenic spots. Swan Mountain National Forest Park is connected with the lake.

(2) Yuelu Mountain Scenic and Cultural Education Zone: Yuelu Mountain is a famous scenic spot in Changsha, with both natural and human landscapes. Yuelu Mountain, located on the west bank of Xiangjiang River, is a part of the hilly area on the western edge of Changliu Basin, with an area of about 3 1 km2, a landscape center of about 8 km2, a length of about 4 km from north to south and a width of about 2 km from east to west. It is an urban mountain scenic spot, with Yubei Peak as the highest peak and an altitude of 300.8 meters. ..

Yuelu Mountain is a collection of deep caves, precipices, famous springs, valleys, beautiful peaks and towering peaks, which can reflect its panorama intuitively and truly on the true color aerial mosaic map. The middle of Yuelu Mountain is high and steep, and gradually decreases from north to south. The south section runs southeast and the north section extends northeast, forming a half-moon arc. Due to the high resolution and high resolvability of aerial photographs, despite the dense vegetation coverage, several driveways and pedestrian walkways can still be identified in the images, and the larger scenic spots such as Yunlugong, Wanjing Garden, Aiwan Pavilion and Scenic Area Management Office are undoubtedly presented. By comparing the topographic map of 1 ∶ 1000 with the tourist map of Yuelu Mountain, other scenic spots and stone walkways can be identified.

Yuelu Mountain has a long history and rich natural resources. There are many places of interest, such as the true face of Lushan Mountain, Yuelu Academy, Baihequan, Huangxing Tomb and Cai E Tomb. In particular, there are more than a dozen universities and a number of scientific research institutes such as Hunan University, Hunan Normal University and Central South University of Technology in the scenic spot, which is an important cultural and educational research base in Hunan and represents another landscape type with rich cultural colors, especially Yuelu Mountain.

(5) Making a three-dimensional guide map model of Yuelu Mountain.

DEM (Digital Elevation Model) is the most important basic data for creating three-dimensional guide map, and its accuracy and quality have great influence on the accuracy of three-dimensional guide map. Structurally speaking, DEM is also a raster image, but the data value of each point represents the elevation value of that point, not the color value of that point.

The compilation of the three-dimensional guide map of Yuelu Mountain was completed in cooperation with the GIS Center of Central South University. DEM data is obtained by 1∶ 10000 topographic map, and nonlinear interpolation with 1 m step according to the contour elevation value of topographic map. In other words, its elevation accuracy is equivalent to or even slightly higher than1:10000 topographic map. The software used is IMAGINE remote sensing image processing software of ERDAS company in the United States.

After the DEM is completed, a surface raster layer will be created. The surface raster layer contains two kinds of data: color and vector data (roads, bridges, scenic spots, etc. ). The vector data of the map is taken from the electronic map and the Yuelu Mountain remote sensing plane guide map, and the color data is obtained from the supervised classification of IMAGINE generated by DEM. The higher the altitude, the greener and bluer the water surface. Aerial photos and satellite photos can also be used in the surface grid layer.

After registering DEM to the surface raster layer, overlay it with IMAGINE and perform image overlay operation. In order to highlight the height difference, the height of Yuelu Mountain has tripled. Due to the limited viewing angle after stretching, it is impossible to observe the whole picture of Yuelu Mountain from one angle and fully reflect its tall and straight shape, so we chose three ideal angles to observe and save the observation results as images.

At this point, the most critical work of the three-dimensional guide map model has been completed, but the roads, bridges and scenic spots at this time are just some simple plane graphics, which are not strong in three-dimensional sense and do not match the lively terrain. Therefore, it is necessary to use image editing software for final trimming and paste it in a suitable and accurate position with three-dimensional graphics. If we strive for perfection, we can use 3DMAX, ULEAD COOL3D and other tools to model different building types with specific projection angles, and then paste the models on the 3D topographic map. In addition, a similar method should be used to mark the text in the appropriate position.