Human Impact Competition

A recent addition to the Geo-Wiki family of VGI data collection tools is A targeted campaign was used to gather data on land cover and human impact through this latest Geo-Wiki branch. Some initial results are presented here. 

The Campaign

The human impact competition was initiated in September 2011. Users were randomly provided with MODIS-sized pixels of 500m resolution and were then asked to answer 3 questions based on what they could see on Google Earth. The questions were:

  1. What is the amount human impact that can be seen in the pixel?
  2. What is the land cover type?
  3. What is the amount of abandoned land visible in the pixel?

In addition, users were asked to enter the date of the image and whether the image was high resolution. The resolution indicates potential difficulties in identifying human impact, land cover and/or abandoned land, especially when users are presented with low resolution imagery.


Validators and Validation Points

More than 60 people took part in the competition with approximately 55,000 points validated in total. Figure 1 summarizes the number of points validated by the top ten competitors (Table 1) along with a score for quality to determine their final ranking. Quality was measured by comparing a set of control pixels derived from experts with the answers provided by the crowd. Factoring in quality actually resulted in changes to the ranking, with 2 competitors with higher validations dropping out of the top ten and two entering due to their accuracy in identifying land cover and human impact. The users were informed of this possibility on a number of occasions so they clearly understood that quality is of utmost importance.

Figure 1: Number of validated points along with score for quality for the top 10 validators.

Rank Name Affiliation  
 1Simone Ortner University of Applied Sciences, Wiener Neustadt, Austria 
 2Rubul Hazarika Gauhati University, Assam, India 
 3 Anna Cipriani Università di Modena e Reggio Emilia, Modena, Italy and Lamont Doherty Earth Observatory of Columbia University, Palisades, New York, USA
 4 Carlos Di Bella National Institute of Agricultural Technology (INTA), Buenos Aires, Argentina 
 5 Ahmed H. Rabia University of Naples Federico II, Naples, Italy 
 6 Alfredo G. García National Institute of Agricultural Technology (INTA), Buenos Aires, Argentina 
 7Mar'yana Vakolyuk IIASA and Centre for Aerospace Research of the Earth (CASRE) Kyiv, Ukraine 
 8Kuleswar Singha Gauhati University, Assam, India 
 9María E. Beget National Institute of Agricultural Technology (INTA), Buenos Aires, Argentina
 10 Stefan Erasmi University of G?ttingen, G?tingen, Germany 
Top 10 Validators of the Human Impact Competition

Land cover

Figure 1: Mapping of the land cover types as validated by the participants

Human Impact

Figure 2: Mapping of Human Impact as validated by the participants

Lesson Learned

Although the campaign was a success with such a large number of points collected over a two month period, a number of issues arose during the competition, which are being used to improve Geo-Wiki. These include:

1.  In the human impact competition we asked users to classify the land cover based on the dominant land cover type. We have now added the ability to indicate how many land cover types there are in an area based on the percentage of occurrence. A grid is overlaid onto the area to help users determine these percentages.

2. The addition of other information from external sources such as flickr, picasa, youtube and twitter to help in making interpretations, particularly with low resolution imagery.

3.  The provision of social networking tools embedded directly within Geo-Wiki so that users can interact, discuss areas that are hard to classify and ask the Geo-Wiki team any questions during the competition.

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Last edited: 25 January 2013


Steffen Fritz

Senior Research Scholar

Ecosystems Services and Management

T +43(0) 2236 807 353


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