Geospatial Technologies for the Geospatial Technologies for the Agricultural Sciences Agricultural Sciences Maggi Maggi Kelly Kelly Assoc. Cooperative Extension Specialist Assoc. Cooperative Extension Specialist Department of Environmental Science, Policy & Management Department of Environmental Science, Policy & Management Director, GIIF Director, GIIF UC Berkeley UC Berkeley Karin Tuxen Karin Tuxen GIIF GIIF College of Natural Resources College of Natural Resources UC Berkeley UC Berkeley Geospatial Imaging & Informatics Facility Geospatial Imaging & Informatics Facility College of Natural Resources @ UC Berkeley College of Natural Resources @ UC Berkeley
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Geospatial Technologies for the Agricultural Sciences
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Geospatial Technologies for theGeospatial Technologies for theAgricultural SciencesAgricultural Sciences
WAAS (can improve to 2WAAS (can improve to 2--5m)5m)
••
DGPS (can improve to 0.1DGPS (can improve to 0.1--1m)1m)
(Your GPS unit must be WAAS(Your GPS unit must be WAAS--
or or DGPSDGPS--compatible!)compatible!)
GOOD PDOPGOOD PDOP
GOOD PDOP GOOD PDOP –– BAD VISIBILITYBAD VISIBILITY
POOR PDOPPOOR PDOP
Image credit: P.H. Dana, GarminImage credit: P.H. Dana, Garmin
What is GIS?What is GIS? GGeographiceographic
IInformationnformation
SSystemsystems
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Entry, editing, storage, query and Entry, editing, storage, query and retrieval, transformation, analysis, retrieval, transformation, analysis, and display & printing of spatial and display & printing of spatial data.data.
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GIS integrates spatial data from GIS integrates spatial data from many sources, scales, and formats.many sources, scales, and formats.
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Key pointKey point: All data in a GIS is : All data in a GIS is georeferencedgeoreferenced, i.e. located by means , i.e. located by means of geographical coordinates with of geographical coordinates with respect to some reference system.respect to some reference system.
What is remote sensing?What is remote sensing?
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The capture of information about the EarthThe capture of information about the Earth’’s surface from a s surface from a distance, usually an airplane or satellite.distance, usually an airplane or satellite.
Blue:Blue:
soil, plants, roads, watersoil, plants, roads, water
Green: Green: vegetation type differences, roadsvegetation type differences, roads
Red: Red: vegetation type differences & manvegetation type differences & man--made featuresmade features
Near infrared: Near infrared: biomassbiomass, , vegveg typestypes, soil moisture, soil moisture
Middle infrared: Middle infrared: moisture in moisture in vegveg and soils, rocksand soils, rocks
Applications for Agricultural Field ResearchApplications for Agricultural Field Research
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Precision agriculture includes the use of GPS, GIS, and remote sPrecision agriculture includes the use of GPS, GIS, and remote sensing ensing to manage practices in variable field conditions.to manage practices in variable field conditions.
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Map, monitor, and manage:Map, monitor, and manage:––
Pests detection and monitoringPests detection and monitoring••
Spray applicationsSpray applications
Image credits: http://www.gisrs.com/Agric.html
GPS Options for Field ResearchGPS Options for Field Research
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Garmin w/ field notesGarmin w/ field notes––
Handheld GPSHandheld GPS
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Field notebookField notebook
––
PROSPROS••
Simple, lightSimple, light--weight, and weight, and inexpensiveinexpensive
––
CONSCONS••
Only gives GPS coordinatesOnly gives GPS coordinates
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Restricted to lower accuracy Restricted to lower accuracy (2(2--15 m error)15 m error)
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Field PDA systemField PDA system––
PDAPDA
––
GPSGPS
––
SoftwareSoftware
––
PROSPROS••
Collects data electronicallyCollects data electronically
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Uses custom programs and Uses custom programs and formsforms
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Overlay GPS points on Overlay GPS points on imagery in the fieldimagery in the field
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Improved accuracy Improved accuracy (up to 10 cm)(up to 10 cm)
––
CONSCONS••
ExpensiveExpensive
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Sometimes NOT userSometimes NOT user--friendlyfriendly
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Less lightLess light--weightweight
Handheld GPS UnitsHandheld GPS Units
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Accuracy is usually 5Accuracy is usually 5--15m; 15m; can be as much as 50m can be as much as 50m due under heavy canopy, due under heavy canopy, PDOP, etc.PDOP, etc.
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Cannot set PDOP Cannot set PDOP thresholdthreshold
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Some have WAAS Some have WAAS differential correction to differential correction to improve accuracy to 2improve accuracy to 2--5m.5m.
Guide to the Handheld Garmin modelsGuide to the Handheld Garmin models
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C C ––
Color displayColor display
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S S ––
Electronic compass and barometric altimeterElectronic compass and barometric altimeter
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X X ––
Expandable memory, new Expandable memory, new SiRFSiRF
GPS for Agricultural Field ResearchGPS for Agricultural Field Research
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What are your accuracy needs?What are your accuracy needs?––
22--15 m 15 m ……handheld units are okayhandheld units are okay
––
<2 m <2 m ……mappingmapping--grade units are grade units are neededneeded
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GPS good for mapping points, lines, GPS good for mapping points, lines, and polygons of relatively small areasand polygons of relatively small areas––
Very large areas should be Very large areas should be mapped/digitized using imagery in a mapped/digitized using imagery in a GIS.GIS.
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How much data will you collect?How much data will you collect?––
Points, lines, AND polygons?Points, lines, AND polygons?
––
Extensive field note taking?Extensive field note taking?
GPS StandardizationGPS Standardization
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Position FormatPosition Format––
How 3How 3--D earth is mapped on aD earth is mapped on a
22--D surfaceD surface
––
Same thing as Same thing as ““projectionprojection””
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Map DatumMap Datum––
Mathematical model that fits Mathematical model that fits the earth to an ellipsoidthe earth to an ellipsoid
GPS StandardizationGPS Standardization
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Latitude/longitude is OK, butLatitude/longitude is OK, but……––
Lat/long is not consistent across Earth.Lat/long is not consistent across Earth.––
Misinterpretation of the three different formats Misinterpretation of the three different formats (degrees(degrees--minutesminutes--seconds, degreesseconds, degrees--decimal decimal minutes, and decimal degrees) can cause error.minutes, and decimal degrees) can cause error.
––
Rounding lat/long numbers can cause error.Rounding lat/long numbers can cause error.
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Use UTMUse UTM––
Numbers represent meters, so each integer is a meter.Numbers represent meters, so each integer is a meter.
––
Split into zones so there are never negative numbersSplit into zones so there are never negative numbers
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Most important thing is to Most important thing is to be consistentbe consistent