Infinity uses a very basic LoS/Cover system -- a target either has partial cover or not. This means a wall that is lower than a model's knees is treated the same as a wall that comes up to the model's neck.
Furthermore, the target model has to be in base contact with the terrain item to get cover. So in the case above if the target model is not touching the wall, there is no obstruction.
Are there any revised Infinity rules for this, either official or house rules?
Thanks