acceptation of earth observation information by gis users national aerospace laboratory, space...

Acceptation of Earth observation information by GIS users

National Aerospace Laboratory, Space DepartmentUNIGIS intake march 2002

Edwin Wisse

16 June 2006

Acceptance of Earth observation 2

Introduction: Earth obseravtion

History 1972, Landsat-1 first dedicated

Earth observation satellite 1986, SPOT-1: 10 metre

panchromatic, 20 metre multispectral

1991, ERS-1: imaging radar 1999, Ikonos: high resolution

optical satellite (1 metre pan, 4 metre multspectral)

Applications Scientific Agricultural and environmental With hogh resolution satellites:

planning and surveying


Introduction: acceptance

Earth Observation has so far failed to evolve into a mature and self-sustainable operational or commercial activity. Hence, it has not allowed the development of a service industry of any economic significance. (Achache, Director of EO ESA, 2003)

In numbers: Public sector (mostly defense) forms 64% of the market. Private sector: mostly telecommunications (planning mobile phone

networks) plus oil and gas Annual growth over 1998-2000: 1.4% (that’s decline)

Problems and solutions Findability. O2 (ESA): build infrastructuur Availability. Rapideye: use Constellations Usability. Error and resolution aspects are not sufficiently

understood and applied

But what are exactly the weaknesses in Earth observation according to users?


Introduction: ideal Earth observation

Satellite watches over Duckburgh constantly (temporal resolution)

Fine tune button for easy zooming (spatial resolution) It’s free! Images can be received from the air (availability)What you see is what you get (error aspects)


Study problem

The question we want answered is:

What factors are decisive in user acceptance of Earth observation information by GIS users?

This can be formulated as two consecutive questions:What are the different factors?How strong do they affect acceptance?

Why GIS users?

Talks with other UNIGIS students showed me that most found EO very interesting and promissing, but very few were aactually using it.

But how can we test acceptance?


Technology acceptance model

Based on the theory of reasoned action, people base their decisions on a chain of factors. Intention to use affects actual usage, and the attitude of a person affects intention.

This was extended to the Technology Acceptance Model. In TAM usefulness and ease of use are introduced. These affect the attitude.

TAM contains methodology for measuring the strenght of the constructs.

TAM has been used to test acceptance of software tools, phones, services etc.



TAM uses a standard scale to measure the relations between the contructs:

Using TestTool in my job would enable me to accomplish tasks more quickly

Using TestTool would improve my job performance ... It would be easy for me to become skilful at using TestTool I would find TestTool easy to use

Standard TAM is based on the perceived usefulness and ease of use constructs.

In later studies factors affecting the constructs have been introduced: enjoyment, functionality, interactivity etc.


Earth observation: sensors and image types

Optical easy to interpret hindered by cloud cover,

especially over the Netherlands

high resolution means small swath

with high resolutions the look angle of the sensor and shadows become significant

Radar: looks through cloud cover coarse resolution sensitive to different

materials than optical


Earth observation: (classified) maps

Thematic maps from EO images: classified maps

Use spectral models to derive soil type, vegetation from pixel values

More channels (colours) give better results

Coarser resolution gives better results

Classified maps either errors (wrongly classified pixels) or they are incomplete


Earth observation: parameters

What are the factors affecting acceptance? (see study problem)

Spatial resolution Temporal resolutionErrors and uncertaintiesRepresentation: file format, how is

the data delivered?Availability: how to find data?

How do these parameters relate to the usefulness en and ease of use constructs?


Modified TAM for Earth observation


Modified TAM: the scale

The modified scale was designed to measure the affect of the parameters on the constructs:

The spatial resolution of optical images is sufficient for my needs Optical images are acquired often enough for my needs Thematical maps (classified images) with a classification error are

usable for me An error-free, but incomplete, thematical map or classified image is

useful for me ... Importing Earth observation imagery and information into my GIS

environment is easy for me I know how to find and order the Earth observation images I need

An additional 4 questions from the standard scale were introduced to measure the affect of intention.


Questionnaire session

ArcGIS user day at NLR:Presentations about EOVisit to ground stationEn de questionnaire sessie

Session:Controlled environment2 sessions of 14 peopleText of the presentation was read

from paperThe subjects used a voting remote

control Interactive interface to select,

compare and zoom into sample images


Results: the subjects group

The subjects group:

Predominantly GIS users with little EO experience (good!)

More than half were from government: municipalities and provinces

Subjects who indicated that they had daily experience with EO were excluded from the following analysis. This left 25 subjects


Results: spatial resolution

The subjects rate: traditional EO imagery (10 metre resolution) neutral high resolution imagery more usefull radar imagery negative


Results: temporal resolution

The subjects rate: Despite the differences between optical and radar there is little

difference in the responses All subjects are neutral to positive to the temporal resolution issues


Results: error aspects

Error aspects related results: Incomplete maps as more

useful than maps with errors A georefencing error is not

acceptable Visulatisation of errors in GIS

leads to high perceived usefulness


Results: usefulness and ease of use constructs

4 questions refered directly to the usefulness and ease of use constructs

Subjects are neutral to positive about usefulness

They see no problems with ease of use


Results

Reliability: The wide spread of he questions

has resulted in a low, but acceptable reliability.

Correlations: Strong correlations between

spatial, temporal and error paramaters and perceived usefulness.

Also a strong correlation between representation and availability and the perceived ease of use.

Smaller (but significant) correlation between perceived usefulness and intention to use.

The perceived ease of use construct is weak in the modified TAM (but that was to be expected)

Construct Items Reliability

perceived usefulness 12 0.3486

perceived ease of use 5 0.4916

Davis’ PU 2 0.7985

Davis’ PEU 2 0.4270

intention to use 2 0.7255

Perceived usefulness

Perceived ease of use

Spatial resolution 0.639 -0.207

Temporal resolution 0.526 0.078

Error aspects 0.501 0.303

Representation 0.323 0.587

Accessibility -0.116 0.580


Conclusions

Earth observation and GIS: Subject group needs high resolution data (1 metre is still not

sufficient), acquisition is already often enough for this group. They are aware of the different errors and would like to see

error representation in their GIS application. Representation and availability are not seen as problems.

Modified TAM: Good first result Ease of use is weakly defined Future study: use less parameters (and more subjects)

Unigis: Unigis provides an excellent opportunity to step out of your

own field of expertise and learn something different

acceptation of earth observation information by gis users national aerospace laboratory, space...

Documents

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earth obseravtion history

surveying slide

resolution aspects

testtool easy

standard tam

tam usefulness