erdas除云方法

erdas>interpreter>radiomatic enhancement>haze reduction
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Software: ArcGIS- ArcVie w - E RDAS - ENVI - H TML
Simple corrections
ERDAS Example
1.) Begin by ope ning the file which you just finished georegistering (or use r:\lawe rs\data\landsat\bbc\my_resample.img). Display the 432 band combination.
2.) Select INTERPRETER > Radiometric Enhancement > Ha ze R eduction option from the main icon bar me nu. Note along the wa y all the other options. The HAZE REDUCTION dialog will appear.
This dia log offers you a chance to see the "model" that will preform a t ransformation on the d ata. Click on the VIEW button t o start the ER DAS Model build. The DeHaze model will be loaded.
This model is very simple. It illustrates the step s that ERDAS will take. The Input Raster is your image, the PSF Kernel is a convolution filter. To understand how one pixel is convolved, imagine that the con volution ke rnel is overlaid on the data file values of the image (in one band), so that the pi xel to be con volved is in the center of the window. The output value for the convolution is, each value in the ke rnel is multiplied by the image pixel value that corresponds to it. The products are summed, and th e total is divided by the sum of th e values in the kernel and assigned back to the cente r pixel. The kernel is then moved to the ne xt pixel.
A High-Fre quency kernel (high pass) has the effect of increasing spatial frequency. That is to say, when this kern el is used on a se t of pexels in which a relatively low value is surrounded by highe r values the low value gets lower. Whe n used with pixels in which a relatively high value is surrounded b y lower value s the high value becomes higher. In this way a simple spatial frequency of ha ze ma y be reduced.
3.) Now fill out the input and output fields of the Ha ze R eduction dialog. The software now knows that the data is Landsat T M data and will now pick a "DeH aze" model for Landsat. Click on VIEW to see it.
The grahic model illu strates the steps that ERDAS will go through. This "model" is specific to Landsat TM data and as you can see it consist of picking between a matrix of weights for either landsat 4 or 5 d ata and the the n determining the majo rity value with a ke rnel, put that dat a out to memo ry and the dete rmining if any pixel has a val ue of zero be fore ma king the output file. I wouldn't try to figure this one out. It is but one of the various approaches.
Fill out the dialog for input and output and click OK. Display your results side by side and look at the spatial profiles of the refle ctence values
I also did a Point_Spread model (not using the model for Landsat Data). Lo ok at t he results.
It looks like more ha ze, but what are the DN values like?
You should do one or both of these mo dels and save a result.
5.) To preform topograp hic correction; Display the Digital Elevation Mod el for the site (r:/users/lawers/data/landsat/bbc/bbc_dem30.img) and then select INTERPRETER > Topographic Analysis > Topographic Normalization.
You will need the following information - SUN_ELEVATION=59.88; SUN_A ZI MUTH=137.92. Remem ber to loo k at the VIEW of the m odel which is being preformed.
I'm glad someone else wrote this one for me. Click Oka y and display your result.
Ma ke some notes about what you see.
Spat ia l Analy sis L aborat ory - Schoo l of Oce ano graphy - Un iversity of Wa sh ing ton。