3,622 reputation
719
bio website barry.rowlingson.com
location Lancaster, United Kingdom
age 48
visits member for 4 years, 1 month
seen 8 hours ago

Here I am.


8h
answered Best practice to perform raster map algebra in open source web GIS?
18h
comment Determine mudflats area from remote sensing images
unsupervised classification is where the algorithm itself works out the classes by looking at the pixels and "clustering" by intensity in the bands. It might not find "mudflats" as a category, or it might find several categories for "mudflats" since smooth mudflats might look different to more rippled mudflats or slightly damp mudflats. In a supervised classification you'd put samples of all those in the "mudflat" training set.
19h
answered Determine mudflats area from remote sensing images
Oct
17
comment scatterplot of two rasters in R
I'm never sure when raw rasters work and when you need values() so I played it cautious without testing!
Oct
17
comment scatterplot of two rasters in R
I suspect you mean "coefficient of determination"?
Oct
17
answered scatterplot of two rasters in R
Oct
9
comment How do I consider entity alignment against slope direction?
This boils down to something like a t-test of two circular variables. Probably best doable via some Monte-carlo test, there may be an implementation in an R package...
Oct
7
comment Extracting data, not colors, from geotiffs in R
If its a categorical map then you just need to convert the colours to hex strings (see rgb()) and build a lookup. Otherwise you need to make a function of r,g,b that returns a single V....
Oct
6
revised Extracting data, not colors, from geotiffs in R
added 133 characters in body
Oct
6
comment Extracting data, not colors, from geotiffs in R
It would be odd for someone to write a GeoTIFF with 8-bit values (0 to 255) to code 1 to 20, but madder things have been done. Just linearly scale the values by multiplying by (19/255) and add one in that case (see my answer for similar).
Oct
6
comment Extracting data, not colors, from geotiffs in R
Actually now I'm not sure what you mean by "the data is a single value in different units altogether". Can you edit to show the code (and give us the data file is poss)?
Oct
6
answered Extracting data, not colors, from geotiffs in R
Sep
25
comment How to find highest kernel density point
I didn't guess - I read the help for density.ppp!
Sep
25
comment How to find highest kernel density point
Fixed. Must always do a final run through. Thanks!
Sep
25
revised How to find highest kernel density point
deleted 2 characters in body
Sep
25
answered How to find highest kernel density point
Sep
25
comment How to find highest kernel density point
p=as.ppp(p) fails (R 3.1.1, latest spatstat) "Can't interpret X as a point pattern"...
Sep
21
awarded  Yearling
Sep
16
comment Why covariance values are different in R and ArcGIS?
The covariance and correlation are unchanged in ArcGIS even with a missing value? You've used the right second layer because I can see STD of layer 2 is sqrt(var(c(1,2,3,4,6,7,8,9)). How many missing values can you add to layer 2 before it changes? Does it just copy layer 1 to layer 2 if missing in layer 2? What does the docs say?
Sep
14
comment Adding a grid and selecting random cells from spatial polygon in r
If you want everything in meters then use spTransform to reproject to a metric coordinate system (commonly a UTM zone or a Danish national grid system) and then work exclusively with that until you have to flip it back to lat-long.