1. A computing system, comprising: a processor; and a memory coupled to the processor and storing program instructions that when executed by the processor cause the processor to at least: receive from a first camera a first image of an inventory location, wherein the first image includes a representation of a plurality of inventory items located at the inventory location; determine from an inventory location data store, an item type corresponding to the inventory location; segment the first image into a plurality of image segments; select a first histogram of oriented gradients (“HOG”) model for a first image segment of the plurality of image segments and a second HOG model for a second image segment of the plurality of image segments, wherein: the first HOG model corresponds to the item type and is representative of a second image of an item of the item type obtained at a first distance or at a first item orientation; the second HOG model corresponds to the item type and is representative of a third image of the item of the item type obtained at a second distance or at a second orientation; process the first image to: generate a first plurality of inventory item feature vectors corresponding to the first image segment, and generate a second plurality of inventory item feature vectors corresponding to the second image segment; compare the first plurality of inventory item feature vectors with the first HOG model; compare the second plurality of inventory item feature vectors with the second HOG model; and count a number of the first plurality of inventory item feature vectors that are substantially similar to the first HOG model and the number of the second plurality of inventory item feature vectors that are substantially similar to the second HOG model, wherein the count is representative of a quantity of items at the inventory location.