Context is critical for minimising ambiguity in object de-
tection. In this work, a novel context modelling framework
is proposed without the need of any prior scene segmen-
tation or context annotation. This is achieved by explor-
ing a new polar geometric histogram descriptor for con-
text representation. In order to quantify context, we for-
mulate a new context risk function and a maximum margin
context (MMC) model to solve the minimization problem of
the risk function. Crucially, the usefulness and goodness
of contextual information is evaluated directly and explic-
itly through a discriminant context inference method and
a context confidence function, so that only reliable con-
textual information that is relevant to object detection is
utilised. Experiments on PASCAL VOC2005 and i-LIDS
datasets demonstrate that the proposed context modelling
approach improves object detection significantly and out-
performs a state-of-the-art alternative context model.