Published inGoogle Earth and Earth Engine·Nov 2, 2021Fast(er) DownloadsEarth Engine by Example While Earth Engine is a powerful system, sometimes you just need to download some data. But if you want to download a lot of little pieces of data that are fast to compute (like image chips or random samples), an Export task using the Earth Engine…Google Earth Engine5 min readGoogle Earth Engine5 min read
Published inGoogle Earth and Earth Engine·May 20, 2021More Buffered Samples with Hex CellsEarth Engine by Example I’ve never had much use for hex maps — until now. In a previous article, I demonstrated how to generate a random sample with buffering to guarantee that no two samples are closer than a given distance. Since then, a (now obvious) idea occurred to me…Google Earth Engine3 min readGoogle Earth Engine3 min read
Published inGoogle Earth and Earth Engine·May 18, 2021Finding Circles, RevisitedEarth Engine by Example In the Earth Engine Code Editor Examples, there’s an example of doing circle finding by kernel convolution. This article will demonstrate another method for circle detection that has a little more flexibility called the Circle Hough Transform (CHT). The usual recipe for CHT is: Smooth the…Hough Transform4 min readHough Transform4 min read
Published inGoogle Earth and Earth Engine·Apr 16, 2021Random Samples With BufferingEarth Engine by Example A common concern when doing land cover classifications is the risk of spatial autocorrelation in sampled data skewing the prediction results or accuracy assessment. One method that can help with this issue is ensuring the training and validation samples are sufficiently spaced using some form of…Google Earth Engine5 min readGoogle Earth Engine5 min read
Published inGoogle Earth and Earth Engine·Apr 15, 2021Runs with ArraysEarth Engine by Example A common problem people struggle to solve with Earth Engine is computing various kinds of runs, especially through time using an Image Collection. Calculating these kinds of values involves looking at a pixel’s temporal neighbors, and Earth Engine collections don’t readily support that. …Google Earth Engine5 min readGoogle Earth Engine5 min read
Published inGoogle Earth and Earth Engine·Apr 15, 2021Histogram MatchingEarth Engine by Example — Histogram matching is a quick and easy way to “calibrate” one image to match another. In mathematical terms, it’s the process of transforming one image so that the cumulative distribution function (CDF) of values in each band matches the CDF of bands in another image. To illustrate what this looks…Google Earth Engine4 min readGoogle Earth Engine4 min read
