  Generating an image from its textual description requires both a certain
level of language understanding and common sense knowledge about the spatial
relations of the physical entities being described. In this work, we focus on
inferring the spatial relation between entities, a key step in the process of
composing scenes based on text. More specifically, given a caption containing a
mention to a subject and the location and size of the bounding box of that
subject, our goal is to predict the location and size of an object mentioned in
the caption. Previous work did not use the caption text information, but a
manually provided relation holding between the subject and the object. In fact,
the used evaluation datasets contain manually annotated ontological triplets
but no captions, making the exercise unrealistic: a manual step was required;
and systems did not leverage the richer information in captions. Here we
present a system that uses the full caption, and Relations in Captions
(REC-COCO), a dataset derived from MS-COCO which allows to evaluate spatial
relation inference from captions directly. Our experiments show that: (1) it is
possible to infer the size and location of an object with respect to a given
subject directly from the caption; (2) the use of full text allows to place the
object better than using a manually annotated relation. Our work paves the way
for systems that, given a caption, decide which entities need to be depicted
and their respective location and sizes, in order to then generate the final
image.
