Robin's Blog

Archive for November, 2011

How to choose a co-ordinate transformation in ArcGIS

When you try and reproject a dataset in ArcGIS (for example, by using the Project Raster¬†tool) you will see a dialog a bit like the one below: The highlighted field wants you to specific a Geographic Tranformation. Although it says that it is optional, it often isn’t (I think the optionality depends on the type […]

Free Julian Day calendar poster download

I often find myself using Julian days as a simple method to represent dates in my code. It’s nice and easy, because every day is simply an integer (the number of days since the beginning of the year) and any time during the day can be represented as a floating point number (the fraction of […]

Please use sensible colours in your maps

If you are creating maps then for goodness sake Use sensible colours!¬† I was helping some undergraduates with some work the other day, and they decided to use the following colour scheme for representing river depth: Deep water: Red Medium-depth water: Bright green Shallow water: Pink Why did they do this? Well, either they were […]