Digital data acquisition

Citing and Permission for use of ASTER data (and others from LP DAAC)

Tue, 29 Jan 2008 18:37:02 +0000

I just got a definitive email response on how to cite ASTER data (or other data from the same source), and that there are no restrictions on their use. I am publishing a paper in ESRI's ArcUser, whose the editor also got this email, so ESRI should now be aware (if they weren't before), that these data are acceptable for publication (you don't have to only use ESRI's data).

Thanks to Janice Wilson for clarifying this!

Matching ASTER Granule ID with Filenames

nico — Mon, 17 Dec 2007 21:46:12 +0000

This question/answer comes from the LPDAAC archives but the link is no longer online so I'm posting the formatted text here. Note that the naming conventions changed in 2003 (see below)

How to convert ASTER EOS-HDF imagery to IMG in ERDAS Imagine 8.7

nico — Sun, 15 Apr 2007 01:42:04 +0000

Imagery from the ASTER instrument on the Terra platform is described at the JPL website. This description text was copied from p.24 of the following PDF file http://edcdaac.usgs.gov/aster/ASTER_GeoRef_FINAL.pdf

Importing ASTER (14DMO) DEM and Imagery into ArcGIS 9

nico — Thu, 15 Mar 2007 15:12:56 +0000

Steps to using ASTER14DMO DEM and Imagery data in ArcGIS 9.1 or 9.2

The ASTER14DMO format file contains 15 TIF files. These include 14 bands of imagery (V1-3n and 3b, S4-S9, T10-T14), and a DEM file. If you have an HDF file see this posting first. DEM 1. Open the TIF file and right-click layer > Data… > Export Data… choose Format: GRID 2. Give it a legal filename for GRIDs (short filename, no spaces or weird characters) 3.

Efficient Georeferencing in Arcmap

nico — Tue, 13 Mar 2007 04:32:56 +0000

Arcmap Map Georeferencing techniques and keyboard shortcuts that save time. Make pyramids before georeferencing. ArcCatalog (or toolbox) can batch Make Pyramids. Choose the reference that you will use to georeference the map. For historic maps and older datums the coordinates that make up the margins of the map frame are often best. In the case of South American topo maps a UTM grid is available but I’ve found the edge Lat/Longs to be more versatile and quicker to reference. Put the map frame in the destination coordinate system/datum (read from edge of paper map).

Aerial Photographs source archive

Sat, 16 Dec 2006 00:06:53 +0000

The following is an extensive list of providers of Aerial photographs (principally covering the USA).

This list was forwarded to Eric Schniter by friend Geoff Smick in environmental consulting, who is a co-worker of this guy:

Chris Zumwalt
GIS Technician
415-454-8868 x35

This is the list:

Importing DEM data from GeoTIFF in Arcmap

nico — Tue, 07 Nov 2006 01:20:55 +0000

Instructions for converting GeoTIFF DEM data to GRID in Arcmap

DEM data often arrive in the form of GeoTIFF that must be converted to GRID for further work in ArcGIS.

1. Acquire SRTM data as GeoTIFF and open in Arcmap. Right-click and Export... Export to GRID format. If you have a lot of grids you can automate this step, see below.

2. Reformat with the following command in Spatial Analyst under Raster Calculator:

setnull ( [GRIDNAME] < 0 , [GRIDNAME] )

That command sets all topographic values less than 0 (sea level) and the no-data collar area to <NULL>.

Converting HDF-EOS (ASTER) imagery to GeoTIFF

nico — Thu, 02 Nov 2006 09:17:42 +0000

How to convert the ASTER imagery (HDF format) into a more widely readable format.

[note: in 2007 some imagery from ASTER is arriving as 15 GeoTIFF files. If your ASTER data is in TIF files see this posting instead]

The program Geomatica Freeview is a good program for browsing and viewing HDF files, but it does not allow you to export to another format.

Datums and Coordinate Systems for GPS users

nico — Wed, 11 Oct 2006 18:02:26 +0000

Quick overview of datums/coordinate systems for GPS use.

The GPS system run by the US Government uses WGS84 datum and decimal degrees as the internal coordinate system.

If you're using a consumer-level GPS and you like to export your data to a GIS in the future, then this coordinate system is probably the most versatile. Also, if you'd like to overlay your data on web maps such as Google Maps "Mashups" then WGS84 decimal Degrees are the format that is needed. In this format you won't have to worry about keeping track of your UTM Zone and the transformation being used.
However you should use the projected UTM coordinate system if you want to make measurements while you are in the field because instead of being in the Degrees the UTM system is in Metric units. You have to use a polar projection in high latitude areas because the UTM system doesn’t extend to the polar regions.
A good review of Datums and coordinate systems is online at Peter Dana’s website
http://www.colorado.edu/geography/gcraft/notes/datum/datum.html

Week 3 - Acquisition of digital data

nico — Wed, 11 Oct 2006 17:06:21 +0000

Exercises: finding datasets, global coverage:

Georeferencing scanned historic maps
Importing GoogleEarth imagery to Arcmap
Locating topographic data
Locating multispectral imagery
Locating vector data

Classroom Topic:

Data acquisition methods for anthropological research.

Generating hydrology from SRTM data

nico — Mon, 02 Oct 2006 02:15:13 +0000

In terrain with some topographic relief a DEM can be used to estimate the position and relative volume of streams under the principal that all streams flow downhill.

STEP 1. Get SRTM data online.

Download the tiles in Arc/Info ASCII if possible, or use HGT or BIL format. DTED is a little more difficult to work with.

SRTM data in 3 arc sec (90m) resolution can be found in either 'research' or 'finished' grade http://SRTM.USGS.GOV (Thanks to NASA and the USGS)

'Finished' grade SRTM data is now available to the public. Finished grade has speckling holes filled and (significantly, for hydrology studies) it has larger rivers "burned in" to the SRTM.

Week 1 - Introduction to ArcGIS and acquiring new data

admin — Sun, 01 Oct 2006 21:39:07 +0000

Classroom topics:

Structure of the class.

Introduction to GIS
Applications in anthropology
Strengths, weaknesses, and critiques
Topics we will cover in this 10 week course

In Class Lab -- Week 1

Part I - Create a shapefile and digitize from a satellite image.

In this exercise we will learn how to create a polygon shapefile by digitizing the polygon from an satellite image of the pyramids of Giza.