FRAGSTATS翻译.docx

1、FRAGSTATS翻译FRAGSTATS accepts raster images in a variety of formats, including ArcGrid, ASCII, BINARY, ERDAS, and IDRISI image files. FRAGSTATS does not accept Arc/Info vector coverages like the earlier version 2. All input data formats have the following common requirements:? All input grids should

2、be signed integer grids, ideally containing all non-zero class values (i.e., each cell should be assigned an integer value corresponding to its class membership or patch type). Note, FRAGSTATS assumes that the grids are signed integer grids; inputting an unsigned integer grid may cause problems. In

3、addition, note that assigning the zero value to a class is allowable, but FRAGSTATS will reclassify all zero cell values to a new class value equal to 1 plus the largest class value in the input landscape. This procedure is necessary because a zero background class value may cause problems in the mo

4、ving window analysis because a background value of zero in the output grid cannot be distinguished from a computed metric value of zero. In addition, a zero class value may cause problems when the landscape contains a border because zero cannot be negative, yet all cells in the border must be negati

5、ve integers). Thus, all zero cells are assumed to be interior (i.e., inside the landscape of interest). For these reasons, it is simpler to avoid the use of zero class values altogether.? All input grids should consist of square cells with cell size specified in meters. For certain input formats (AS

6、CII and BINARY), this is not an issue because cells are assumed to be square and you are required to enter the cell size (in meters) in the graphical user interface. However, FRAGSTATS assumes that all other image formats (ArcGrid, ERDAS, and IDRISI) include header information that defines cell size

7、. Consequently these images must have a metric projection (e.g., UTM) to ensure that cell size is given in metric units.There are some additional special considerations for each input data format, as follows:(1) Arc Grid created with Arc/Info. Note, to use Arc Grids you must have ArcView Spatial Ana

8、lyst or ArcGIS installed on your computer and FRAGSTATS must have access to a certain .dll file found either in the ArcView Bin32 directory (for ArcView Spatial Analyst users) or the ArcGIS Bin directory (for ArcGIS users). Specifically, a path to the corresponding dll library file should be specifi

9、ed in the environmental settings under NT or Windows 2000 operating systems, or a path statement included in the autoexec.bat file, e.g., under Windows 98, as follows:Windows NT: You can add the necessary Path variable or edit the existing one via the Control panel - System Properties - Environment

10、tab. Add a new variable or edit the existing Path variable in the system variables, not the user variables (this will require administrative privileges). Add the full path to the appropriate .dll file. If you are using ArcView Spatial Analyst, the required file is the avgridio.dll file and it is typ

11、ically installed in the following path: esriav_gis30arcviewbin32. If you are using ArcGIS, the required file is the aigridio.dll file and it is typically installed in the following path: esriarcinfoarcexe81bin. Note, your software version number and path may be different so be sure to locate the .dl

12、l file on your computer and enter the correct path. If you are using both Spatial Analyst and ArcGIS, then you can enter either or both paths to the Path system variable. Windows 2000/XP: You can add the necessary Path variable or edit the existing one via the Control panel - System Properties - Adv

13、anced tab - Environment Variables button. Add a new variable or edit the existing Path variable in the system variables, not the user variables (this will require administrative privileges). Then, following the instructions above for. Windows 95/98: You must add the necessary Path statement to the a

14、utoexec.bat file. First, search your computer for the autoexec.bat file and open it using any text editor. Then, either add a Path statement or edit the existing one. Add the full path to the appropriate .dll file. If you are using ArcView Spatial Analyst, the required file is the avgridio.dll file

15、and it is typically installed in the following path: esriav_gis30arcviewbin32. If you are using ArcGIS, the required file is the aigridio.dll file and it is typically installed in the following path: esriarcinfoarcexe81bin. Thus, the path statement should look something like: PATH c:esriav_gis30arcv

16、iewbin32. Note, your software version number and path may be different so be sure to locate the .dll file on your computer and enter the correct path. If you are using both Spatial Analyst and ArcGIS, then you can enter either or both paths to the Path system variable. If you are adding the path to

17、an existing path, simple use a semicolon to separate the unique paths in the Path statement. After saving the file you will need to reboot your machine for the change to take effect.(2) r. Each record should contain 1 image row. Cell values should be separated by a comma or a space(s). Note, it will

18、 be necessary to strip (delete) the header information from the image file if it exists, but be sure to keep it for later reference regarding background cell value, # rows, and # columns.(3) 32-bit binary file, no header; no other limitations.(4) 16-bit binary file, no header. Patch ID output file,

19、if selected, will be output in signed 32-bit integer format to accommodate a greater number of patches. In addition, because moving window analysis requires floating points, if moving window analysis is selected, the output grids produced will be 32-bit floating point grids.(5) 8-bit binary file, no

20、 header. Patch ID output file, if selected, will be output in signed 32-bit integer format to accommodate a greater number of patches. In addition, because moving window analysis requires floating points, if moving window analysis is selected, the output grids produced will be 32-bit floating point

21、grids.(5) ERDAS image files (.gis, .lan, and .img). FRAGSTATS accepts images from both ERDAS 7 (.gis and .lan) and ERDAS 8 (.gis, .lan, and .img), but the limitations are somewhat different, as follows: ERDAS 8 Files.FRAGSTATS accepts .gis, .lan, and .img files used by current versions of ERDAS IMAG

22、INE, including signed 8-, 16-, and 32-bit integer grids. While .gis and .lan file formats are supported, their limitations make them less practical than .img (see discussion of ERDAS 7 files below). Care should be taken when preparing the data to be used with FRAGSTATS, especially when importing dat

23、a from other formats (for instance from Arc Grid). Be sure to set the import options to signed integer. Regardless of the input integer format (8-, 16-, or 32-bit), the patch ID output file created by FRAGSTATS will be a signed 32-bit integer, and if moving window analysis is selected, all output gr

24、ids will be 32-bit floating point. Multi-layered files are not rejected, but only layer one is processed and the outputs are all single layered. As noted above, cells must be square, not rectangular, and the measurement unit should be meters. If the measurement unit is not specified, then it is assu

25、med to be meters. The cell size and measurement unit specification can be changed within ERDAS Imagine using the ImageInfo tool - Change Map Model from the Edit menu. The projection information existing in the input file is passed unchanged to the output files. FRAGSTATS does not use this informatio

26、n internally. ERDAS 7 files.- FRAGSTATS accepts .gis and .lan files used by ERDAS 7, which are limited to unsigned 8- or 16-bit integer grids. FRAGSTATS will accept both 8-bit and 16-bit integer files and it will reject multi-layered files. While .gis and .lan file formats are supported, their limit

27、ations make them less practical than .img. In particular, ERDAS 7.x files are limited to unsigned integers (i.e., only positive integers), therefore landscape borders (which require negative class values) cannot be represented. Another consequence of this particular limitation is that FRAGSTATS-gene

28、rated patch ID files will not fill the non-landscape cells (i.e., no data cells) with the usual value (minus the background class value), but with zero values. The restriction to 8- or 16-bit integers imposes some limitations when using the FRAGSTATS on large grids. Specifically, unsigned 16-bit int

29、egers can only take on values up to 65,534. Thus, class ID values are limited to integers within this range (note, this should not be a problem, since it is unlikely that anyone would have more than 65,534 patch types). Similarly, patch ID values in the patch ID output grid optionally produced by FR

30、AGSTATS are limited to the same range, effectively limiting the number of patches in this output grid to 65,534. If the grid contains more than this number of patches, FRAGSTATS will not be able to output a unique ID for each patch and the user will have to somehow distinguish among patches with the

31、 same ID. Finally, because the moving window analysis requires 32-bit output files (in order to output floating point values), moving window analysis is not supported with ERDAS 7 files.(6) IDRISI image files (.rdc). IDRISI currently supports signed 8- or 16-bit integers and 32-bit floating point gr

32、ids. This imposes some limitations when using the FRAGSTATS on large grids. Specifically, signed 16-bit integers can only take on values between -32,768 and 32,767. Thus, class ID values are limited to integers within this range (note, this should not be a problem, since it is unlikely that anyone w

33、ould have more than 32,767 patch types). Similarly, patch ID values in the patch ID output grid optionally produced by FRAGSTATS are limited to the same range, effectively limiting the number of patches in this output grid to 37,767. If the grid contains more than this number of patches, FRAGSTATS will not