From March 7, 2008 to March 21, 2008, the ASD spectral data of typical features were measured in the Bian Du Kou encrypted observation area. Through the grid spectrum measurement results of ground features, the spatial variation characteristics and laws of ground feature subpixel spectrum are explored, and the spectral characteristics of ground features in cold and arid areas are analyzed. On this basis, it provides data for the spectral model database of typical ground object target and background model, and provides basic data for remote sensing image simulation and spatial scale conversion of remote sensing data.

  ASD FieldSpec frtm (Boulder, Co, USA) was used for measurement. The spectral range is 350nm-2500nm. The spectral resolution is 3nm in visible near-infrared band and 10nm in short wave infrared band.

  The survey time, features and contents are as follows: On March 7, 2008, the instrument tested the spectra of dry soil, wet soil, straw, snow and grassland in biandukou area, and arranged quadrats for observation. On March 21, 2008, the surface was covered with about 10cm snow. The spectral characteristics of the snow at biandukou were measured, and no quadrat was arranged. On March 17, 2008, the observation data were synchronized with TM.

  Sampling method: select the center of the area in a flat and homogeneous area to lay the quadrat. Select 90m respectively × 90m、450m × 450m is used as the grid sampling area of three different scales. At 90m × 90m、450m × 9 in 450m quadrat area × 9 grid division, so that the three quadrats are divided into 81 10m × 10m、50m × 50m sub grid. The specific meaning of the three grids is: 30m × 30m、150m × 150m is the basic resolution of satellite sensor. On this basis, the contribution of single pixel and eight neighborhood pixels to the central pixel is considered. Each pixel is divided into 9 sub pixels to explore the law between the sub-pixel spectrum and the whole pixel spectrum. Due to the long distance between sample points, 90m × The 90m quadrat is realized by laying the quadrat with measuring rope and marker post, with a height of 450m × The 450m quadrat is realized by laying control points with GPS. The sampling method is profile measurement, which represents the spectrum of the whole quadrat pixel by measuring the central profile of each sub quadrat, and replaces the full sampling of the sub quadrat by measuring the statistical average of the spectrum for many times. The survey route adopts patrol mode to ensure the quasi synchronization of spectrum measurement.

  The measurement data is in ASCII format and can be opened with Notepad, WordPad and other software. The first 5 lines of the file are the file header, which describes the relevant information of the data; The next two columns of data, one for wavelength and one for reflectance (percent reflectance). The file in the original data is in ASD's own format and opened with ASD viewspec software.