L3DB6H

Lloyd Bosworth : archaeologist | human | beard

This QGIS tutorial is part of a series detailing my journey moving from ArcGIS to QGIS and how I’ve relearned familiar ArcGIS workflows. I’ve been using ArcGIS for many years and the move to QGIS has at times presented quite a steep learning curve. Some of what I have learned has come from trial and error, but the greater majority has come from searching forums and other blogs and I try to credit these sources as I go along. Writing these articles is both a personal aide-memoire and a way to cement the new skills I am learning, but if they are helpful to others, then all the better.

QGIS tutorial for archaeologists wanting to create survey grids and export as points to use with a GPS or Total Station.

Creating and Orienting Vector Grids in QGIS 2.18

In this QGIS tutorial I will use a real-life geophysical survey to detail how I use QGIS to create polygon grids, how I orientate them to fit the area of interest and how I export the grid as points to use with a GPS or Total Station system.

In archaeology, laying out a grid before a survey or excavation is an essential part of keeping a fieldwork project organised. Grids can be aligned to real-world coordinates, such the British National Grid here in the UK, or can be on an arbitrary alignment, called a site grid, chosen to best fit the terrain or landscape. A site grid will commonly use a field boundary, verge, fence line or other linear feature as a baseline from which to measure out the grid.

Gridding out, as it’s called, can be done quickly in the field by one or two people using surveyor’s tapes. I’m fortunate to have access to a GPS Rover which can achieve the same result as using hand tapes, but much more quickly and with millimetre accuracy. The other benefit of using a GPS is that the grid can be created in QGIS in the office and transferred precisely onto the field.

QGIS Tutorial Contents

  1. Creating the grid
  2. Orienting the grid
  3. Converting polygons to points
  4. Exporting point layers
  5. How does this workflow compare with ArcGIS?

(more…)

Merge Multiple Rasters Using Cell Statistics

A simple and elegant way to merge multiple raster datasets in ArcMap is to use Cell Statistics in Spatial Analyst Tools. While there are many ways to merge raster datasets in ArcMap, the most common, Mosaic, can be tricky, as an empty raster must first be created into which the raster tiles are merged. Getting any parameters wrong here could mean a failed merge.

A map I’ve recently created required me to merge several SRTM raster tiles. Normally I’d jump to Mosaic to merge the raster tiles, but remembering this can often be a slow and problematic process, I looked for an alternative method. This search led me to discover that Cell Statistics (Spatial Analyst Tools > Local), a tool I’ve never used before, can merge rasters quickly and without fuss. (more…)

Res Gestae Divi Augusti, Ara Pacis, Rome, Italy

3D Model of the Res Gestae Divi Augusti on the wall of the Ara Pacis museum, Rome, Italy. Created from 13 images taken on an iPhone 5s. While the wall is completely flat, the model has a slight curve due to uncorrected lens distortion in the camera.

Res Gestae Divi Augusti (The Deeds of the Divine Augustus) is the funerary inscription of the first Roman emperor, Augustus, giving a first-person record of his life and accomplishments. The Res Gestae is especially significant because it gives an insight into the image Augustus portrayed to the Roman people. Various inscriptions of the Res Gestae have been found scattered across the former Roman Empire. The inscription itself is a monument to the establishment of the Julio-Claudian dynasty that was to follow Augustus. Wikipedia

Res Gestae Divi Augusti, Ara Pacis, Rome, Italy
by l3db6h
on Sketchfab

How to Fix AutoCorrect Options in Word 2016

Why is the right click > AutoCorrect menu missing from Word 2016?

how to enable right click autocorrect options in word 2016I’ve always liked using Office. Sure, it has its problems, but over the years I’ve just learned to work around them or with them. I also have Office for my Mac which is, honestly, rubbish. As I’m a really sloppy typist, the most rubbish part of Office for Mac is the lack of AutoCorrect options when right clicking. I always thought this was a deliberate act of spite on Microsoft’s part, but alas no, as they have now inflicted this on PC users with Word 2016.

Click the image on the right to see how daft it is to have left out this option. A fresh, out-of-the-box installation of Word 2016 doesn’t have ‘Microsoft’s’ in the dictionary. In any previous version of Word you would right click > AutoCorrect > AutoCorrect Options and then tell Word how you want AutoCorrect to handle the new word, in this case, capitalising the first letter. Now compare this to the limited options available in Word 2016. (more…)

Is Facebook phishing for email passwords?

There are really only two rules for keeping an email account secure: choose a strong password and don’t share that password with anyone else. Follow these two rules and you reduce your chances of being hacked to almost zero. If you do share your password, you have lost control of it. It’s as simple as that. Even if you trust the person you have given it to, and made them promise really really hard that they won’t tell anyone else, there is nothing you can do to stop them.

So why is Facebook asking me for my email account password?

I have recently re-joined Facebook after deleting my old account some four years ago. My old account was such an unholy mess of personal and professional that the thought of untangling it all seemed to be more trouble than it was worth, hence the nuclear option.

Now I’m back, I find that Facebook hasn’t changed much at all. Old friends are easy to find and there is the snowball effect that for each friend request I send, I receive many more requests in return.

One thing that is new, or at least something I’d never seen before, is the option to have Facebook scrape the contact list of my email address for people I know, and they will automatically be sent friend requests on my behalf. What a great tool! (more…)