How-to Tech and geospatial

Arcview on a mac?

A little while ago I purchased a new macbook pro after discovering that they now run Windows. As far as laptops go, MBPs are brilliant: they take no time at all to to configure out of the box, are simple to use, backup and recover. They are wonderful as a writing and research tool and lets face it, the MBP looks cool as well.

Archaeologists however can never really move away from using Windows in some way. Various important software packages are only available on this OS: Sofware for radiocarbon calibration, survey, CAD, GPS and GIS are typically shackled to Windows. One of the most crucial Windows programs I use for research and consultancy work is Arcview. For the uninitiated, Arcview is a fairly capable and widely used GIS program that allows one to display, manage and analyse spatial data such as site locations, environmental data, infrastructure and development information and so on.

Arcview will only ever be a windows application and so jumping over to a Mac has mean that I needed to get Windows working on my Mac well enough so that I can seemlessly move between my Windows and Mac environments, without restarting my computer. Although this is all possible it has taken me a while to get it working well on my Mac and so in this post I simply wanted to highlight some key tips for people in similar situations.

  1. Bite the bullet and install bootcamp. There are other ways to run windows in a mac, without needing to partition your hard disk, but after multiple attempts I found that they were all really quite slow when it came to working with large datasets. Bootcamp will run any windows program at normal (i.e. ‘native’) windows speeds. Use it, it’s a free part of OSX.
  2. Give yourself space to move. When you create your bootcamp partition, give yourself at least 6 gigabytes for Windows PLUS whatever is required for your windows applications. If you think you will have 30 gig of data, give youself that much space. I initially tried leaving my arcview data on the Mac partition however it was very slow to load on the windows side and some datasets would not load at all. I then tried an external firewire hard drive which was faster, but still sluggish and caused other problems. With arcview at least, there is nothing as fast or functional as having your program and data on the same drive. Use an external drive for backups.
  3. Format your bootcamp partition in NTFS. Bootcamp guides will tell you that you must use FAT32: ignore that advice. There are benefits and disadvantages to both and despite what you read the main point is that both drives will be accessible from inside each operating system when you eventually install the VM software. Most importantly, if you use NTFS then you can very easily backup the whole bootcamp/windows installation using your mac and reinstall without a fuss when things go wrong. So, once you proceed to installing windows on your bootcamp partition make sure you tell the Windows installer to format your partition as NTFS.
  4. Purchase and install parallels. Once you have everything installed in bootcamp and Windows has done its crazy ‘update for 2 days’ thing, shut down Windows and restart your mac in OSX and then purchase and install parallels. After you install it on your mac running windows is very simple. You simply run parallels and then select ‘my bootcamp’ from the main menu and your Windows bootcamp install will open in its own window (which is resizable, etc). From here you can run arcview.
  5. Create a clean install recovery image. It may take a few days to get your Windows XP install and other software and external device drivers (GPS for instance) running. Once you are happy that you have the perfect set up then download a nifty little Mac program called winclone. This program makes a compressed copy (disk image) of your entire windows partition that includes all of your Windows updates, drivers and software. This backup image can be reloaded onto your NTFS Windows partition at any time so that you can quickly revert to a clean install without having to go through the entire process again. This is useful to two reasons. (a) Windows will eventually die on you at a very inconvenient time, thus requiring a full reinstall, and (b) if you find you need more or less space on your windows partition, you can resize the partition and reinstall a fresh copy of windows very quickly. I needed to resize my Windows partition from 10 gig to 40 gig and using Winclone, managed to do so in less than an hour!

And that’s it! After running arcview for several weeks this way I have not noticed any reduction in performance or any other errors, even with large raster datasets that often cause problems.

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How-to Tech and geospatial

Archaeological survey and geotagging

As a consultant archaeologist time is always valuable and so it is important to have a robust system for recording and capturing field data quickly. By the same token, shoddy field recording practices result in mistakes and at best this results in lost time or a poor report, and at worst can lead to missed sites or poor management outcomes. So developing techniques to help achieve a good balance between efficiency and quality are critical and emerging digital technologies have a lot of potential in this area.

On large projects, there can be a lot of field data to record: site data (including multiple site types), varying survey methods, ground visibility, previous ground disturbance, environmental characteristics and so on. In addition to the paperwork keeping track of  digital photos and GPS data is also critical, after all an incorrect coordinate or photograph number can cause major problems when it comes time to write up your results long after you have left the field. Trying to fill out a range of different proformas and document your digital data can be difficult enough on its own, but the addition of other factors such as hot sun, high humidity and friendly insects really can upset the best field recording system.

Because of all this, I place a lot of effort into my recording system and in particular, over recent months I’ve been looking for ways to help manage my digital data. Particularly digital photos, GPS waypoints and GPS tracks recorded during a survey. One useful trick I’ve discovered is that it is possible to ‘sync’ or cross reference your digital photos and GPS data. Digital cameras automatically embed exif data within the digital image file, and this includes information such as camera settings, date, time and so on. Similarly, the ‘autotracking’ option on most handheld GPS devices records useful data with each point they record – whether that be an automatically created track point, user-created waypoint and so on.

For a while now I have used the exif and GPS metadata to help make sense of problematic digital photographs of sites or places where your paper record is in error (ie, an incorrect coordinate or site number). In this case, it is fairly straightforward process to cross-check the time and date of your waypoint or track point with the time and date of your photos, so that you can fill in the gaps in any missing information. It is a nice fall back position when your memory and field notes have partially failed you and although simple, it is generally quite a reliable way of verifying problematic data. Importantly though, you do need to make sure you have the time and date correctly set on your devices!

In recent years ‘geotagging’ software has started to emerge and these enable you to automatically embed coordinates recorded in your GPS into digital photos taken at around that time. In short, you tell the software where your photos and GPS data files are and the software will automatically sync the exif data from your digital images with the metadata on your GPS, thus generating a series of spatially referenced photos. There are a range of benefits to doing this: you can just use geotagging for maintaining and archiving your own photos, however for me the attraction is the potential for using geotagged photos to report on and communicate results with clients or other stakeholders (such as Indigenous Traditional Owners or the broader community). In a consulting context, this method has potential for presenting your results in a more interactive and interesting way. For example, it is possible to send your geotagged photos to free web or software applications (via Google Earth or Google Maps) so that they display in an interactive format.  With the addition of survey results (eg. site data, survey locations, development areas, etc) it should be possible to create an interactive presentation for your client or others that could be uploaded to the web, sent on a disk or so on.

Geotagging has a lot of potential to help archaeologists with managing their field data and I’ll write more about my trials in this area in future. For web veterans who’ve been following trends in web technology over the past few years, this is all probably be nothing new however I’m yet to see archaeologists talk openly about how their experiences using these types of things. What other ways are archaeologists  using these and other technologies to help with recording and managing field data? Let me know in the comments below!

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