Movement data in GIS and the AI hype

This post looks into the current AI hype and how it relates to geoinformatics in general and movement data analysis in GIS in particular. This is not an exhaustive review but aims to highlight some of the development within these fields. There are a lot of references in this post, including some to previous work of mine, so you can dive deeper into this topic on your own.

I’m looking forward to reading your take on this topic in the comments!

Introduction to AI

The dream of artificial intelligence (AI) that can think like a human (or even outsmart one) reaches back to the 1950s (Fig. 1, Tandon 2016). Machine learning aims to enable AI. However, classic machine learning approaches that have been developed over the last decades (such as: decision trees, inductive logic programming, clustering, reinforcement learning, neural networks, and Bayesian networks) have failed to achieve the goal of a general AI that would rival humans. Indeed, even narrow AI (technology that can only perform specific tasks) was mostly out of reach (Copeland 2018).

However, recent increases in computing power (be it GPUs, TPUs or CPUs) and algorithmic advances, particularly those based on neural networks, have made this dream (or nightmare) come closer (Rao 2017) and are fueling the current AI hype. It should be noted that artificial neural networks (ANN) are not a new technology. In fact, they used to be not very popular because they require large amounts of input data and computational power. However, in 2012, Andrew Ng at Google managed to create large enough neural networks and train them with massive amounts of data, an approach now know as deep learning (Copeland 2018).

Fig. 1: The evolution of artificial intelligence, machine learning, and deep learning. (Image source: Tandon 2016)

Machine learning & GIS

GIScience or geoinformatics is not new to machine learning. The most well-known application is probably supervised image classification, as implemented in countless commercial and open tools. This approach requires labeled training and test data (Fig. 2) to learn a prediction model that can, for example, classify land cover in remote sensing imagery. Many classification algorithms have been introduced, ranging from maximum likelihood classification to clustering (Congedo 2016) and neural networks.

Fig. 2: With supervised machine learning, the algorithm learns from labeled data. (Image source: Salian 2018)

Like in other fields, neural networks have intrigued geographers and GIScientists for a long time. For example, Hewitson & Crane (1994) state that “Neural nets offer a fascinating new strategy for spatial analysis, and their application holds enormous potential for the geographic sciences.” Early uses of neural network in GIScience include, for example: spatial interaction modeling (Openshaw 1998) and hydrological modeling of rainfall runoff (Dawson & Wilby 2001). More recently, neural networks and deep learning have enabled object recognition in georeferenced images. Most prominently, the research team at Mapillary (2016-2019) works on object recognition in street-level imagery (including fusion with other spatial data sources). Even Generative adversarial networks (GANs) (Fig. 3) have found their application in GIScience: for example, Zhu et al. (2017) (at the Berkeley AI Research (BAIR) laboratory) demonstrate how GANs can generate road maps from aerial images and vice versa, and Zhu et al. (2019) generate artificial digital elevation models.

Fig. 3: In a GAN, the discriminator is shown images from both the generator and from the training dataset. The discriminator is tasked with determining which images are real, and which are fakes from the generator. (Image source: Salian 2018)

However, besides general excitement about new machine learning approaches, researchers working on spatial analysis (Openshaw & Turton 1996) caution that “conventional classifiers, as provided in statistical packages, completely ignore most of the challenges of spatial data classification and handle a few inappropriately from a geographical perspective”. For example, data transformation using principal component or factor scores is sensitive to non-normal data distribution common in geographic data and many methods ignore spatial autocorrelation completely (Openshaw & Turton 1996). And neural networks are no exception: Convolutional neural networks (CNNs) are generally regarded appropriate for any problem involving pixels or spatial representations. However, Liu et al. (2018) demonstrate that they fail even for the seemingly trivial coordinate transform problem, which requires learning a mapping between coordinates in (x, y) Cartesian space and coordinates in one-hot pixel space.

The integration of spatial data challenges into machine learning is an ongoing area of research, for example in geostatistics (Hengl & Heuvelink 2019).

Machine learning and movement data

More and more movement data of people, vehicles, goods, and animals is becoming available. Developments in intelligent transportation systems specifically have been sparked by the availability of cheap GPS receivers and many models have been built that leverage floating car data (FCD) to classify traffic situations (for example, using visual analysis (Graser et al. 2012)), predict traffic speeds (for example, using linear regression models (Graser et al. 2016)), or detect movement anomalies (for example, using Gaussian mixture models (Graser & Widhalm 2018)). Beyond transportation, Valletta et al. (2017) describe applications of machine learning in animal movement and behavior.

Of course deep learning is making its way into movement data analysis as well. For example, Wang et al. (2018) and Kudinov (2018) trained neural networks to predict travel times in a transport networks. In contrast to conventional travel time prediction models (based on street graphs with associated speeds or travel times), these are considerably more computationally intensive. Kudinov (2018) for example, used 300 million simulated trips (start and end location, start time, and trip duration) as input and “spent about eight months of running one of the GP100 cards 24-7 in a search for an efficient architecture, spatial and statistical distributions of the training set, good values for multiple hyperparameters”. More recently, Zhang et al. (2019) (at Microsoft Research Asia) used deep learning to predict flows in spatio-temporal networks. It remains to be seen if deep learning will manage to out-perform classical machine learning approaches for predictions in the transportation sector.

What would a transportation AI look like? Would it be able to drive a car and follow data-driven route recommendations (e.g. from waze.com) or would it purposefully ignore them because other – more basic systems – blindly follow it? Logistics AI might build on these kind of systems while simultaneously optimizing large fleets of vehicles. Transport planning AI might replace transport planners by providing reliable mobility demand predictions as well as resulting traffic models for varying infrastructure and policy scenarios.

Conclusions

The opportunities for using ML in geoinformatics are extensive and have been continuously explored for a multitude of different research problems and applications (from land use classification to travel time prediction). Geoinformatics is largely playing catch-up with the quick development in machine learning (including deep learning) that promise new and previously unseen possibilities. At the same time, it is necessary that geoinformatics researchers are aware of the particularities of spatial data, for example, by developing models that take spatial autocorrelation into account. Future research in geoinformatics should incorporate learnings from geostatistics to ensure that resulting machine learning models incorporate the geographical perspective.

References

Congedo, L. (2016). Semi-Automatic Classification Plugin Documentation. DOI: http://dx.doi.org/10.13140/RG.2.2.29474.02242/1
Copeland, M. (2016) What’s the Difference Between Artificial Intelligence, Machine Learning, and Deep Learning? https://blogs.nvidia.com/blog/2016/07/29/whats-difference-artificial-intelligence-machine-learning-deep-learning-ai/
Dawson, C. W., & Wilby, R. L. (2001). Hydrological modelling using artificial neural networks. Progress in physical Geography, 25(1), 80-108.
Graser, A., Ponweiser, W., Dragaschnig, M., Brandle, N., & Widhalm, P. (2012). Assessing traffic performance using position density of sparse FCD. In Intelligent Transportation Systems (ITSC), 2012 15th International IEEE Conference on (pp. 1001-1005). IEEE.
Graser, A., Leodolter, M., Koller, H., & Brändle, N. (2016) Improving vehicle speed estimates using street network centrality. International Journal of Cartography. doi:10.1080/23729333.2016.1189298.
Graser, A., & Widhalm, P. (2018). Modelling Massive AIS Streams with Quad Trees and Gaussian Mixtures. In: Mansourian, A., Pilesjö, P., Harrie, L., & von Lammeren, R. (Eds.), 2018. Geospatial Technologies for All : short papers, posters and poster abstracts of the 21th AGILE Conference on Geographic Information Science. Lund University 12-15 June 2018, Lund, Sweden. ISBN 978-3-319-78208-9. Accessible through https://agile-online.org/index.php/conference/proceedings/proceedings-2018
Hengl, T. Heuvelink, G.B.M. (2019) Workshop on Machine learning as a framework for predictive soil mapping https://www.cvent.com/events/pedometrics-2019/custom-116-81b34052775a43fcb6616a3f6740accd.aspx?dvce=1
Hewitson, B., Crane, R. G. (Eds.) (1994) Neural Nets: Applications in Geography. Springer.
Kudinov, D. (2018) Predicting travel times with artificial neural network and historical routes. https://community.esri.com/community/gis/applications/arcgis-pro/blog/2018/03/27/predicting-travel-times-with-artificial-neural-network-and-historical-routes
Liu, R., Lehman, J., Molino, P., Such, F. P., Frank, E., Sergeev, A., & Yosinski, J. (2018). An intriguing failing of convolutional neural networks and the coordconv solution. In Advances in Neural Information Processing Systems (pp. 9605-9616).
Mapillary Research (2016-2019) publications listed on https://research.mapillary.com/
Openshaw, S., & Turton, I. (1996). A parallel Kohonen algorithm for the classification of large spatial datasets. Computers & Geosciences, 22(9), 1019-1026.
Openshaw, S. (1998). Neural network, genetic, and fuzzy logic models of spatial interaction. Environment and Planning A, 30(10), 1857-1872.
Rao, R. C.S. (2017) New Product breakthroughs with recent advances in deep learning and future business opportunities. https://mse238blog.stanford.edu/2017/07/ramdev10/new-product-breakthroughs-with-recent-advances-in-deep-learning-and-future-business-opportunities/
Salian, I. (2018) SuperVize Me: What’s the Difference Between Supervised, Unsupervised, Semi-Supervised and Reinforcement Learning? https://blogs.nvidia.com/blog/2018/08/02/supervised-unsupervised-learning/
Tandon, K. (2016) AI & Machine Learning: The evolution, differences and connections https://www.linkedin.com/pulse/ai-machine-learning-evolution-differences-connections-kapil-tandon/
Valletta, J. J., Torney, C., Kings, M., Thornton, A., & Madden, J. (2017). Applications of machine learning in animal behaviour studies. Animal Behaviour, 124, 203-220.
Wang, D., Zhang, J., Cao, W., Li, J., & Zheng, Y. (2018). When will you arrive? estimating travel time based on deep neural networks. In Thirty-Second AAAI Conference on Artificial Intelligence.
Zhang, J., Zheng, Y., Sun, J., & Qi, D. (2019). Flow Prediction in Spatio-Temporal Networks Based on Multitask Deep Learning. IEEE Transactions on Knowledge and Data Engineering.
Zhu, J. Y., Park, T., Isola, P., & Efros, A. A. (2017). Unpaired image-to-image translation using cycle-consistent adversarial networks. In Proceedings of the IEEE international conference on computer vision (pp. 2223-2232).
Zhu, D., Cheng, X., Zhang, F., Yao, X., Gao, Y., & Liu, Y. (2019). Spatial interpolation using conditional generative adversarial neural networks. International Journal of Geographical Information Science, 1-24.