Extract lake surface

Question

Hello. Thank you in advance for any reply!

I use EVI to help extract water surface of a lake. The result is acceptable but not accurate. I don't want to include the extra small pixel plots when counting the total pixel number of the large lake. How can I erase the "noise" pixels? I've marked "noise" out in the second pic. BTW, this is a raster file and has been reclassified into two categories: 0 for Non-lake, 1 for lake (Blue)

DanPatterson_Retired · Answer

Interesting ... I would agree with Darren, however, unless you have greatly oversimplified what you consider noise, there are some regions that have smaller clusters yet you haven't circled them.  Would be fair to say, that you didn't circle all the noise?  What about that big lump in the South East corner... is that noise too?

So follow Darren's suggestion, perhaps with a focal majority with a moderate sized neighbourhood first to get rid of speckle.  Then do the RegionGroup incrementally until you get most of what you call noise identified

DarrenWiens2 · Answer

See this help page. Start at Identifying Clusters with Region Group. Basically, Region Group, Extract By Attributes (or Con), Nibble.