Those of you complaining about the weather may feel validated by this headline from CNN (article here). For the over 1 in 10 Americans work in agriculture and related industries (source), this has real consequences. The increased rain this spring delayed planting, and in some places planting was prevented altogether. The Washington Post has some… Continue reading US Satellite Images and #NoPlant19
Today I'm continuing a series on sources of spatial data (see past posts on aerial images and DEMs). Soil maps are useful for all sorts of applications, like deciding where to place a trial in a larger field so that all the treatments are on the same soil type or determining the drainage class of… Continue reading Data Downloads: Soil Maps
I broke out SAGA again this week to do some soil interpolations. I don't usually use inverse distance weighting (IDW) for much because you can't generate error maps or use covariates with this method. For this project I needed to make some maps in IDW to compare back to other methods. I'm using IDW for… Continue reading Inverse Distance Weighting in SAGA
Sometimes getting a layer to be displayed precisely how you want it can be a tedious process in QGIS. Fortunately, there is a way to save that style so you can apply it to the same layer in another project, or to another layer with similar attributes. Most of the time I use layer style… Continue reading Saving Layer Style Files in QGIS
Are you as obsessed with ColorBrewer as I am? I am making a map where I color Ohio counties based on region, and used ColorBrewer to pick colors. The first thing I did was go to ColorBrewer and find a qualitative color set for 5 categories of data. Next I used the HEX codes provided… Continue reading Getting Category Colors into QGIS from ColorBrewer
Over the last month or so I've had a little series about how we describe positions on the globe and how we visualize spherical space on a 2D map. I started with big picture information, like why we care about map projections. Last week began giving more concrete advice for picking a projected or unprojected… Continue reading EPSG Numbers and Coordinate Reference Systems
More map making! When you're first starting a new project and have data files in different projections, you can still view all your data together at once, using something called on-the-fly projection (a common feature of most GIS software). On-the-fly projection displays all your files using your "project CRS" and lets you have map layers… Continue reading Selecting a Projection for Spatial Analysis
Before I get off the datum topic, I want to share a little bit about what datum the National Geodetic Survey (NGS) is moving towards. The NGS is a part of NOAA, the National Oceanic and Atmospheric association. If you use weather.gov for anything, you're familiar with the outputs from NOAA. The current official datums… Continue reading New Datum for North America
Earlier in the week I gave a quick overview of map projections. Today I'm covering a related topic--datums. North American Datum 1983 is the basis for a lot of common map projections, and World Geodetic System 1984 is the series of latitude and longitude most commonly used on consumer GPS devices. But first, what's a… Continue reading What’s a datum?
At the most basic level, map projections are how we turn the 3D earth surface into something flat. There are polar projections that look at the globe from the top or bottom view, or more common projections that are centered near the equator. Map projections are really easy to overlook, but have large impacts on… Continue reading What’s a map projection?