Simply put, a heatmap is a graphical representation of the location of one or more players within a playing field. This representation is based on information that can be collected in different ways.
From coaching teams to journalists and fans, the use and analysis of heatmaps in football is widely spread. Some of the most common uses are understanding which parts of the field were occupied during a match by a certain player, or preparing matches by analysing the expected position of opponents and understanding to what extent tactical planning was followed in the post-match analysis, etc.
But most users don't know that football heatmaps are created using different techniques.
Events vs Geolocation
The most important aspect to consider when building a heatmap is how to collect the data that will be used for its construction. In that sense, there are two main ways to design heatmaps:
event datasets
geolocation datasets (also known as tracking)
In event-based heatmaps, all the actions performed by a player during a match (shots, crossing passes, fouls, offside, etc.) are labelled with their corresponding Euclidean position and then used as input to infer where the player was located during the match. The advantage of event-based heatmaps is that they are easier to create, although, they are not as accurate in demonstrating which area of the field was covered by the player.
Meanwhile, tracking or geolocation data sets are built with the help of "tracking devices" like GPS, which capture the players’ precise location at regular intervals of time, reflecting the real position of a player. Geolocation-based heatmaps are formed by millions of data points which make it much more precise and clear. Additionally, it is way more reliable in terms of the player's actual position, thus better fulfilling the purpose for which heatmaps were created in the first place.
Differences Between Heatmaps: Case Analysis
First case: Central defender.
(Defended goal: the one on the left.)
Although in this case, both maps provide a similar image concerning the area they demarcate, we can see that the intensity varies substantially. While the event-based map does not detect a large presence of the player in the center of the field, the map built using geolocation data shows that in reality, the center of the field was the sector where the central defender in question was positioned in the most.
While the maps themselves may not seem to be that different, the conclusions we could draw from them are. The reality is that in this case, the defender was a part of the team whose players most of the time positioned themselves in the opponent's half of the field, which resulted in the player often being located in the center — something that the event-based heatmap does not reflect.
Second case: Central forward.
(Defended goal: the one on the left.)
This is an ideal case that shows the limitations of event-based heat maps. If we were to look at the event map, it would generally be impossible to determine where the player was situated in the field to perform further analysis. What’s more, we wouldn't be able to draw conclusions about the forward's positioning during the game or understand their playing style.
On the other hand, with the geolocation-based heatmap, we can detect that the player is a forward who predominantly moves through the central lane of the field. Additionally, they spent most of their time in the vicinity of the penalty area with very little positioning in their half of the football pitch.
How to Get Your Own Football Heatmap?
For a price similar to a pair of football boots, you can get yourself your own OLIVER GPS tracker allowing you to see your own heatmap like an elite player in addition to health and athletic metrics. And even more: in contrast with other GPS trackers in the market, because OLIVER is placed on your leg, it can also produce ball interaction metrics like power kicks, ball touches, dribling and more.
Aitor Puñal, OLIVER’s ambassador from Marbella FC, obtained this heatmap using OLIVER in the match against Real Jaén, in which his club got promoted to Segunda Federación.
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