Recently in GIS Category

This post displays a 3D model of one of the sunken plazas from the site of Pukara, Puno, Peru. During July, 2009 I was visiting excavations by my colleague Liz Klarich (Smith) and using the opportunity to practice photogrammetry on large architecture that had been previously reconstructed. The sunken plaza shown was excavated and reconstructed in the 1970's under Plan COPESCO. In the past, I had collaborated with Liz on aspects of mapping the site of Pukara. The sunken plaza has always captured my interest. This model was the first large architectural feature I attempted to record using photogrammetry. The uneven surface of the ichu grass presented some challenges, but these were overcome by aggressive decimation of the surface. The model was generated with PhotoScan and is displayed on this website as a PDF. The file is large, it may take a moment to download, and may strain computers with low RAM.

This post displays a 3D model of a pithouse at the site of Jiskairumoko, Rio Ilave, Peru. The excavations were performed in 2000. The model was generated with PhotoScan and is displayed on this website as a PDF. The file is large, it may take a moment to download, and may strain computers with low RAM. The model was generated as an experiment to see if 3D reconstructions can be created from archival excavation photos. This proof of concept demonstrates that such reconstructions are possible. 

Over at the PublicLaboratory, they have come up with a nice simple and inexpensive telemetry kit for balloon aerial photography (BAP). The information the unit collects should help with image georeferencing. I suspect that the data could potentially be exploited by applications like Palentier that was written by Mark Willis and M. Stange.

Archaeologist and elite low elevation aerial photographer Mark Willis recently posted a wonderful and informative tutorial on how to create a DEM from a Photosynth Point cloud. The photographs used in his tutorial example were captured by KAP, and the site is Palmitopamba in Ecuador. KAP is probably the most inexpensive LEAP technique, so this was a great proof of concept. Mark also strove to use free and open source applications through the entire work flow. Again, this low cost approach means that the methods should be available to nearly any researcher. One of the stages in Mark's procedures draws inspiration from an earlier post on this site regarding the transformation of structure from motion point clouds to real world coordinates. Mark simplified and clarified the process. This was exciting for me because it was Mark's earlier work with photosynth that stimulated my interests in KAP and structure from motion photogrammetry.

This post describes the process of recording surface artifacts by means of geotagged and hierarchically coded photographs.

Version 9.3 of ArcMap permits you to bring in kml files created in Google Earth. However, if you do this you will find that the features are not accompanied by descriptions or folders. If you have locations organized within Google Earth into various folders, and if they have any descriptions or names that you would like to preserve when bringing into ArcMap, then use the following kml_to_shp script instead, available at: http://arcscripts.esri.com/details.asp?dbid=15603.

Here is the description from the ESRI Support Center website: "This script converts features in a KML file to an ESRI shapefile. KML files can be created by digitizing features in Google Earth. These data must be converted to a shapefile format before they can be used in a GIS. The script provides an easy method to convert these kml features to shapefiles. The shapefile retains the names, descriptions, and the Google Earth folder of the kml features. The script is run out of ArcToolbox and will work with any license level of ArcGIS 9.2 and 9.3. The tool's documentation describes its use. The accompanying word document describes how to load the toolbox into ArcToolbox."

I highly recommend this if you are using Google Earth to digitize information that you intend to use in ArcMap. Many thanks to Carrie Hritz for bringing the script to my attention.

This link can be used to gain free access to the ESRI virtual campus. The catalog of ESRI courses can be found here. Free access to Virtual Campus courses is a great way to cover basic ground on the use of GIS. Students are strongly encouraged to explore this fantastic free resource. Thanks to George Chaplin for bringing it to my attention.

This post provides updated documentation on communication between a Leica TCR 1105 total station and a laptop computer. Previously, I suggested that formatting the PCMCIA card on a laptop computer would provide a solution for transferring files from the total station to a laptop. This solution worked for a while, but yesterday I experienced a problem in the field that indicates formatting the PCMCIA card with windows is a very bad solution. While shooting points with the total station, I got an error message saying "Memory Failure" and I was asked if I wanted to format the card. I replied no, and attempted to proceed with the job. While the error occurred, I was attempting to position the gun using the orientation and height tranfer function. The error on the memory card would not allow the gun to orient. I eventually had to reformat the card on the total station. This means that all data on the card is lost. Fortunately, I had backed up all data on the card so reformatting was not an issue. However, it easily could have been a major loss, right?

After reformatting the card on the gun, there was no problem with gun orientation and no error warnings arose for the rest of the day. At the end of the workday, I attempted to transfer the files from the PCMCIA card to the laptop computer. While attempting to do this, I got the "Incorrect Function" error and the card would not read. Yes, back to square one and I did not want to reformat the card and lose all of the days work.

Today, I returned to Huacho (Peru) where I had a serial to USB cable stored for possible situations just like this. Previously, I had not been successful in getting this conversion cable to work properly. Today, it thankfully worked. Here is the make of the cable and what I did.

Cable make: Gigaware 6-tf USB-A to Serial Cable. It came with Driver CD 26-949. The cable has a box attached to it, and it is not a "simple" USB to Serial. It is a "fancy" one that has drivers and accepts some of the communication issues that Serial cables require. I strongly suggest having one of these or a similar cable up one's sleeve. Here is the URL:
http://www.radioshack.com/product/index.jsp?productId=3120513


Procedures for Windows XP:
1) I installed the drivers for the cable using the provided CD.
2) Then I attached the cable (w/o the gun or anything attached to the cable).
3) I waited for Windows to recognize the cable and to tell me that my new hardware was ready to use. It seems that Windows did an internet search for the driver. Strange considering that I believe the driver was just installed from the CD, but I fear that one may need an internet connection to do this. The lack of an internet connection may have been the reason this cable did not work successfully in Pukara (Peru).
4) I attached the Lemo cable (the one with the five pins, two notches, and the red line) on the Leica to its communication port (the one with the five holes and the two notches).
5) I attached the Serial to USB cable (still plugged in) to the Serial end of the Lemo cable that was just plugged into the Leica.
6) On windows, I opened up the System control panel and went to the Device Manager. There I looked for the RadioShack USB to Serial Cable and made note of which COM port it was using. In this case, the cable used COM5.
7) Then I put the total station into Geocom mode and started up Leica Geo Office.
8) I made sure that the settings on the COM5 port were correctly set in LGO data exchange manager.
9) Browse to the card and retrieve the necessary file.

In the end, I think this is a much better solution than formatting the PCMCIA in Windows. Note: from reading the reviews of the cable, I fear that this solution may not work with either Vista or Win 7--just be aware...

A new title from the National Academy Press

"As digital technologies are expanding the power and reach of research, they are also raising complex issues. These include complications in ensuring the validity of research data; standards that do not keep pace with the high rate of innovation; restrictions on data sharing that reduce the ability of researchers to verify results and build on previous research; and huge increases in the amount of data being generated, creating severe challenges in preserving that data for long-term use.

Ensuring the Integrity, Accessibility, and Stewardship of Research Data in the Digital Age examines the consequences of the changes affecting research data with respect to three issues - integrity, accessibility, and stewardship-and finds a need for a new approach to the design and the management of research projects. The report recommends that all researchers receive appropriate training in the management of research data, and calls on researchers to make all research data, methods, and other information underlying results publicly accessible in a timely manner. The book also sees the stewardship of research data as a critical long-term task for the research enterprise and its stakeholders. Individual researchers, research institutions, research sponsors, professional societies, and journals involved in scientific, engineering, and medical research will find this book an essential guide to the principles affecting research data in the digital age."

I wanted a device that would serve two simultaneous purposes 1) track caloric effort as I move across space and 2) geocode photographs. Neither of these purposes requires high accuracy GPS, but these tasks do require a small GPS device. The Garmin Forerunner 405CX seems like a perfect device.

This Monday, a new global DEM based on ASTER was released. Through the LPDACC, Craig has obtained a large portion of western South America. These DEMs are now included in the Department of Anthropology GIS data archive.

1. Download data from WIST via LPDACC
2. Wait for confirmation email
3. Pull files from FTP directory indicated in confirmation email
4. Unzip the compressed archive using 7-Zip
5. Move the individual zipped tiles to the root directory and unzip all tile components to this root, a series of tif and xml files are produced. Write over the readme.pdf file, these are identical in all cases.
6. Launch ArcCatalog and build pyramids using the "Batch Build Pyramids" tool.
7. Do something else while that grinds away.
8. More soon...

From the first looks, the data are very noisy. So noisy, they they are not yet useful for archaeological/anthropological research. Perhaps areas where cloud cover is not a constant problem will fare better, but the eastern cordillera of the Andes is not looking good.

Many areas of agriculture are impacted by salinization. This problem can be particularly acute in arid regions. ASTER provides a means by which soil salinity can be examined. Below is the ENVI band math used to calculate a soil salinity index image from ASTER imagery. The index is based on Al-Khaier's (2003) MS thesis and it is validated with field measurements of soil salinity.

The band math is as follows:
(float(b4)-float(b5)) / (float(b4) + float(b5))

The equation must be performed with the float parameter.

Craig is presently applying this transformation to examine the spatial pattern of salinity in relation to the distribution of q'ochas in the northern Lake Titicaca Basin.

REFERENCE
Al-Khaier, F.
    2003    Soil Salinity Detection Using Satellite Remote Sensing. Masters of Science, International Institute for Geo-Information Science and Earth Observation.

Another Interesting Reference:
14.00 Fernando Caceres, Hamid Ali-Ammar, Eric Pirard (Universite de
Liege, Belgium)  - Mineral mapping in salt lakes from Sud Lipez
(Bolivia) using ASTER images.

Notes on integrating data from a Leica Total Station into ArcGIS.

Some hints on looping
This post suggests that record by record looping is not possible. Specifically, it states "You can't pass a row object to a gp tool" The first thread gives python code for taking a directory of feature classes and calculating pathdistance from those. The second thread tries to calculate costdistances on several records in a single file. The conclusion is that the single file with multiple records needs to be converted into multiple files each with one record. I believe that the crime analysis tools has the capability of taking multiple records and making a theme from each record.

Reading to the bottom of the post it looks like there is a python solution which will loop through.

Some notes on pathdistance mapping related to the guide written by Nico

Nico's most recent notes can be found here.

Here is the command line for PathDistance:
PathDistance_sa Places C:\WorkSpace\PathDis_Plac2 # dem5792 # 'BINARY 1 45' dem5792 'TABLE C:\WorkSpace\ToblerAway.txt' # C:\WorkSpace\PathDis_Bk2

Here is the command line for CostPath
CostPath Qocha_Centroid PathDis_Plac3 PathDis_Bk3 C:\WorkSpace\CostPat_Qoch1 EACH_CELL ORIG_FID

Strategies for creating profile graphs in ArcMap

The links below lead to a couple of interesting tools for conducting viewshed analysis in ArcMap.

ViewShed for each DEM point / Weighed Distance

http://arcscripts.esri.com/details.asp?dbid=13500

This aml had to be run from workstation. Note: On first run, the aml failed. N Craig has contacted the author. Craig has a revised version.

Automate viewshed analysis

http://arcscripts.esri.com/details.asp?dbid=14687

Burn multipatch into DTM custom geoprocessing tool

http://arcscripts.esri.com/details.asp?dbid=15173
This allows for buildings and other objects to be burned into a dem so that surface analysis can be performed in urban spaces.

Had some GPS data and was trying to label it. The labels did not show. Searched in the ESRI form and found the following helpful hint. The post suggests the need to repair geometry. It reads:

Use ArcToolbox to repair geometry.

ArcToolbox --> Data Management Tools --> Features --> Repair Geometry

This procedure fixed the problem

Sometimes, for cartographic purposes the map maker wants only to label some features for a given layer. This can be done in ArcMap through the use of SQL statements.


In the following example, the cartographer has a data layer called "Strat" and the map should not illustrate features on this layer that are called "Bone", "Chert Fla", or "FAR".

To exclude these three specific categories from labels use the following expression:
NOT "Strat" = 'Bone' AND NOT "Strat" = 'Chert Fla' AND NOT "Strat" = 'FAR'

Within ArcToolbox there are two tools for projecting shapefiles.

If the projection is not defined use Define Projection (Management)
When transforming from one projection to another use Project (Management)

Problem: The inability to georeference a raster in ArcMap is likely caused by the fact that the target raster is in a different projection than the active map.

Solution: Use ArcToolbox to reproject the raster into the current projection. Either select the projection from the list or import it from one of the other properly projected layers.

This post details notes on joining tables with ArcView3.x and using this software to make the joins permanent.

The following are a couple of GPS units that are used with a camera for geotagging. I do not use one of these units, I use a Garmin Forerunner 405cx. The advantages are that the unit is a wrist watch and it also has a heart rate monitor. The disadvantage is that the 405cx will only run for eight hours. During fieldwork I frequently have battery problems. Another disadvantage is that the 405cx does not output digital compass information.

GlobalSat BT-359 review

Qstarz BT Q1300 review

ATP PhotoFinder Mini review and another and yet one more and still another.

This post contains some notes on ArcMap Field Calculator expressions that are useful for analysis of polygons.

The following expressions can be used to calculate various parameters of polygons.

A_i as the Area of polygon i, and L_i as its perimeter length, and B_i as the area of a circle with perimeter L_i, then example measures include:

Perimeter/Area ratio (P1A):

Algebraic Formula:

ArcMap Field Calculator Expression: ([Shape_Length]/[Shape_Area])

Because the value of the index changes with the size of the figure, this ratio is unsatisfactory for most comparative applications.

Perimeter²/Area ratio (P2A):

Algebraic Formula: 

ArcMap Field Calculator Expression: ([Shape_Length]^2/[Shape_Area])

If preferred, this index, or its square root may be adjusted so that its value equals 1 when applied to a circle of the same area as A_i.

Shape Index or Compactness ratio (C):

Algebraic Formula:

_{ArcMap Field Calculator Expression:} Sqr([Shape_Area]/(([Shape_Length]^2)/12.56))

This ratio is dimensionless (it is unaffected by the size of the polygon) and it has a value of 1 for a circular region and a range of [0,1] for all plane shapes. Sometimes the index is computed as [1‑C_i].

Many useful functions are available at ESRI's ArcScripts. I also bookmark scripts that look especially useful for archaeology or anthropology. However, sometimes figuring out how to add this new script into ArcMap is so frustrating that it can feel like one is about to have their head chopped off...To help minimize these frustrations, this post details information on how to add user created scripts to ArcMap.

Scripts are written in a number of different languages. Each of these requires slightly different methods to connect the script to ArcMap. It can be confusing to figure out how the scripts need to be integrated into the program so that the scripts can be used. Descriptions are given for adding functions in the following formats:

• Arc Macro Language (AML)
• Avenue
• Visual Basic (VB, VBA, VBScript)
• Python
• Model Builder

Guide adapted from http://www.acadweb.wwu.edu/GIS/tut/ArcScripts.htm

Software, tutorials, and other links related integrating SketchUp and ArcMap

The link below leads to Nico's notes on cost-distance mapping in ArcMap.This is a very very good place to go for information on how to run Tobler's hiking function using ArcMap.

http://mapaspects.org/courses/gis-and-anthropology/workshop-2009-viewshed-and-cost-distance/ii-cost-distance-2009

This post contains information on how to download and integrate National Elevation Database digital elevation models (DEMs) into ArcMap.

This post describes how to create new points based on the input of a coordinate pair. The process might be useful for plotting individual sites or other observations. Note, rather than reading in a text file of X,Y coordinates the procedures described in this post involve manual coordinate input of data via a digitizing interface.
 

This post contains notes on calculating volumetric estimates from an excavation DEM.