实验四 使用ENVI进行影像镶嵌.doc

实验四 使用ENVI进行影像镶嵌
[实验目的]：掌握ENVI影像镶嵌处理的知识，在何种情况下需要进行影像镶嵌，影像镶嵌时需要注意哪些问题。
[实验内容]：
1. 基于像素的影像镶嵌
2. 基于地理坐标的影像镶嵌
3. 镶嵌时的色彩均衡
[实验准备]：
数据：文件夹 envidata/avmosaic
基于像素的影像镶嵌（Pixel-Based Mosaicking）
File
Description
dv06_2.img
AVIRIS Scene 02
dv06_2.hdr
ENVI Header for above
dv06_3.img
AVIRIS Scene 03
dv06_3.hdr
ENVI Header for above
dv06a.mos
Mosaic Template for end-to-end AVIRIS mosaic
dv06b.mos
Mosaic Template for feathered overlapping AVIRIS mosaic
dv06_fea.img
Feathered Mosaic image
dv06_fea.hdr
ENVI Header for above
基于地理坐标的影像镶嵌（Georeferenced Mosaicking）
File
Description
lch_01w.img
Warped, histogram matched image
lch_01w.hdr
ENVI Header for above
lch_01w.ann
Cut-line feathering annotation for above
lch_02w.img
Warped, histogram matched image
lch_02w.hdr
ENVI Header for above
lch_a.mos
Mosaic Template for Georeferenced Image Mosaicking
lch_mos1.img
Georeferenced mosaic result
lch_mos1.hdr
ENVI Header for above
镶嵌过程中的颜色平衡（Color Balancing During Mosaicking）
File
Description
mosaic1_equal.dat
A subset from a Landsat 7 ETM image for which a histogram equalization stretch has been applied to each band independently
mosaic1_equal.hdr
ENVI Header for above image
mosaic_2.dat
Another subset from the same Landsat 7 ETM image, without any stretching applied
mosaic_2.hdr
ENVI Header for above image
[实验步骤]：
一、基于像素的影像镶嵌
Map → Mosaicking → Pixel Based from the ENVI main menu.
输入并放置影像。
1.Select Import → Import Files from the Pixel Based Mosaic dialog.
2.In the Mosaic Input Files dialog, click Open File, navigate to the avmosaic directory, and select the file dv06_2.img.
3.In the Mosaic Input Files dialog, click Open File again and select the file dv06_3.img.
4.In the Mosaic Input Files dialog, hold down the Shift key on your keyboard and click on the dv06_2.img and dv06_3.img filenames to select them. Click OK.
5.In the Select Mosaic Size dialog, specify the mosaic size by entering 614 for the X Size and 1024 for the Y Size.
6.In the YO text box, enter a value of 513 and press the Enter key on your keyboard. The dv06_3.img is placed directly below dv06_2.img.
7.In the Pixel Based Mosaic dialog, select File → Apply. When the Mosaic Parameters dialog appears, enter the output filename dv06.img and click OK to create the mosaic.
8.Display the mosaicked image by clicking on the dv06a.mos band name in the Available Bands List and then clicking Load Band.
二、基于地理坐标的影像镶嵌
1.Map → Mosaicking →Georeferenced from the ENVI main menu.
2.Select File → Restore Template and select the file lch_a.mos.
3.查看顶层影像、切割线和虚拟未羽化的镶嵌影像。
1)In the Available Bands List, select the file lch_01w.img and display as a gray scale by clicking on the band name and then the Load Band button.
2)In the Main Image window, right-click to display the shortcut menu and select Toggle → Display Scroll Bars to turn on scroll bars. Click the horizontal scroll bar until a good portion of the image is visible.
3)From the Main Image Display menu, select Overlay → Annotation to start the Annotation dialog.
4)In the Annotation dialog, select File → Restore Annotation and choose the file lch_01w.ann to display the red cutline used to blend the two images in this mosaic.
5)From the Available Bands List load the lch_02w.img into a new display and examine the nature of the cutline with respect to this image.
6)Select File → Open Image File from the ENVI main menu and choose lch_a.mos as the input file. From the Available Bands List, load this image into a new display and examine the non-feathered edge between the two images that were used to create the mosaic.
4.创建羽化后的镶嵌影像
1)In the Map Based Mosaic dialog, select File → Apply. In the Mosaic Parameters dialog, enter the output filename lch_mos.img and click OK to create the feathered mosaic.
2)Close the two image display windows containing the individual warped images and load the mosaic image into a new display.
3)Compare the feathered mosaic to the non-feathered mosaic using image linking and dynamic overlays.
三、镶嵌时的色彩均衡
1.创建未经色彩均衡化处理的镶嵌影像
1)Start the ENVI Georeferenced Mosaic function by selecting Map → Mosaicking → Georeferenced from the ENVI main menu. The Map Based Mosaic dialog appears.
2)Select Import → Import Files.
3)In the resulting file selection dialog, choose the Open File button, then navigate to the mosaic1_equal.dat file in the avmosaic directory, then select Open.
4)In the Mosaic Input Files dialog, choose the Open File button again, and this time select the mosaic_2.dat file in the avmosaic directory, then select Open.
5)In the Mosaic Input Files dialog, select the mosaic_2.dat file, then hold down the Shift key and select the mosaic1_equal.dat file. Select the OK button.
2.RGB彩色镶嵌预览
The default behavior is that for three-band images, ENVI will automatically create an RGB display in the mosaic preview, using the first band as red, the second as green and the third as blue. But if the image has more than three bands, then the mosaic preview will show just a grayscale version of Band 1. Of course, if your mosaic input images have only one band, then the preview display will show that band in grayscale.
1)At the bottom of the Map Based Mosaic display window, right click on the name of the mosaic1_equal.dat file, and choose Edit Entry.
2)In the resulting dialog, for Mosaic Display, choose RGB.
3)For Red choose 1, for Green choose 2, and for Blue choose 3. This tells ENVI to load Band 1 for the red color gun, Band 2 for the green color gun, and Band3 for the blue color gun when making the mosaic preview display.
4)Click OK. You can see that the mosaic1_equal.dat image is now displayed in color in the mosaic preview.
5)Repeat steps 1 through 3 for the other file in the mosaic.
3.输出未经色彩均衡化处理的镶嵌影像。
From the Map Based Mosaic display window choose File → Apply.
In the resulting Mosaic Parameters dialog, enter mosaic_unbalanced.dat for the Output Filename, then choose OK. The resulting mosaic will be entered into the Available Bands List when it is finished.
Display the new mosaic in an RGB display with Band1 as red, Band2 as green, and Band3 as blue.
4.输出经色彩均衡化处理的镶嵌影像
1)Right click on the name of the mosaic1_equal.dat file in the Map Based Mosaic dialog, nd choose Edit Entry.
2)At the bottom of the resulting dialog, under Color Balancing, choose Adjust. This indicates that this image’s contrast will be adjusted to match the other image. Choose OK.
3)Now right click on the name of the mosaic_2.dat file, and choose Edit Entry.
4)In the resulting dialog, under Color Balancing, choose Fixed. This indicates that the contrast of this image will not be changed. The other image will be adjusted to match this image. Choose OK.
5)From the Map Based Mosaic display window choose File / Apply.
6)In the resulting Mosaic Parameters dialog, there is now a Color Balance using option near the bottom. Leave this value at stats from overlapping regions. The color balancing is usually better when based on statistics calculated from only the overlapping regions. The other option, stats from complete files, is used when there is little or no overlap between the mosaicked images.
7)Enter mosaic_balanced.dat for the Output Filename, then choose OK. The resulting mosaic will be entered into the Available Bands List when it is finished.
8)Display the new mosaic in an RGB display with Band 1 as red, Band 2 as green, and Band 3 as blue.
5.End the ENVI Session

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