Gap Fill Landsat 7 SLC-OFF Images

PANCROMA is the Simple yet Powerful GIS software application for gap filling Landst 7 SLC-Off images with powerful image registration utilities. Trial download PANCROMA gap fill or buy it now for only USD $49.95!

What is Gap Filling?

The Landsat 7 satellite suffered a partial failure in 2003 when its Scan Line Corrector (SLC) unexpectedly stopped operating. As the Landsat satellite orbits the earth a mirror scans side-to-side to collect the image data. Wedge shaped gaps are created as a result of the combination of orbital tracking and side-to-side sweeping. When it was working, the SLC corrected these gaps. The SLC failure has resulted in systematic gaps (black stripes) in every Landsat image collected since that time.

Can Anything be Done to Correct the Gaps?

Due to the nature of the failure, the gap data is not directly recoverable. However PANCROMA provides two algorithms to fill in the gaps in Landsat 7 images using data collected before the gap failure. The first method typically cuts data from pre-2003 Landsat images and transfers this information (after histogram matching) into the gap image. The second (often more effective) method uses a computational approach that synthesizes gap pixels by combining information in the gap image and a pre-2003 image.

How Effective are the PANCROMA Gap Filling Algorithms?

No gap filling technique is perfect, and the results are very dependent on the commonality between the source and target images, especially with respect to snow and cloud cover. However PANCROMA gap filling algorithms can produce remarkable corrections in many instances. Examples of typical gap filling results are shown in the images below. The first shows the target image with gaps. The second shows the image after gap fill correction. (These results are considered typical of the simple transfer method. You can often achieve much better matches by more careful image selection and using the computational method.)

[Before and After Gap Filling]

Before and After Gap Filling

How Do I Register my Images before Gap Filling?

Landsat images must be co-registered prior to gap filling. PANCROMA offers a powerful set of subsetting and image registration utilities, including semi-automatic three band and fully automatic six band utilities. See a full set of Videos showing how it is done.

Can I Pan Sharpen My Image After Gap Filling?

Yes. See the See the Pan Sharpening Landsat Gap Filled Images Tutorial on the White Papers link at this site.

Try PANCROMA Gap Filling for Yourself

Trial download PANCROMA gap filling or buy it now for only USD $49.95!

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