1. Quality Assessment for
Crowdsourced Geographic
Information
Martijn van Exel
Geodan S&R

2. www.geodan.nl
The Challenge
> Hundreds of thousands of users
contribute information
> Each individual has his own
intents, purposes,
motivations,knowledge and skill
level, tools
> No moderation and a minimal
imposed data model
> Uneven geographical spread of
contributor efforts

3. www.geodan.nl
The Challenge
> Therefore:
> No uniform lineage
> No consistent levels of:
– Data and metadata completeness
– Positional accuracy
– Temporal accuracy
> How to assess
data quality?

4. www.geodan.nl
Crowd Quality
> A novel approach to assessing quality of
crowdsourced geographic information
> Leveraging user and data dynamics unique to
crowdsourcing:
– User Rating
– Feature version
– Feature age and
persistance
– Spatial Flux

5. www.geodan.nl
Advantages
> No reference dataset required
– All metrics can be derived from the dataset itself
> Appreciative of local variations in quality
unique to crowdsourcing

6. www.geodan.nl
Geodan S&R
President Kennedylaan 1
1079 MB Amsterdam (NL)
Tel: +31 (0)20 – 5711 311
Fax: +31 (0)20 – 5711 333
E-mail: info@geodan.nl
Web: www.geodan.nl
Copyright © Geodan 2006
This document is provided for information purposes only and the information herein is subject to change without notice. Geodan does
not provide any warranties covering and specifically disclaiming any liability in connection with this document. Geodan is a registered
trademark. All other company and product names mentioned are used for identification only and may be trademarks of their respective
owners. All pictures and illustrations are provided for information only and do not necessarily represent a realistic visualization of the
services described in this document.

7. www.geodan.nl
Geodan S&R
President Kennedylaan 1
1079 MB Amsterdam (NL)
Tel: +31 (0)20 – 5711 311
Fax: +31 (0)20 – 5711 333
E-mail: info@geodan.nl
Web: www.geodan.nl
Copyright © Geodan 2006
This document is provided for information purposes only and the information herein is subject to change without notice. Geodan does
not provide any warranties covering and specifically disclaiming any liability in connection with this document. Geodan is a registered
trademark. All other company and product names mentioned are used for identification only and may be trademarks of their respective
owners. All pictures and illustrations are provided for information only and do not necessarily represent a realistic visualization of the
services described in this document.