A Binder Module that operates to discern progress of a flow model comprising a plurality of construction actions (201-207) representing a building project for a building site , based on at least one image captured at the building site associated with the flow model , the module comprising: a processor that operates, based on executing a set of instruction stored in a memory to: select an object for evaluation assigned to a construction action comprised in the flow model; from a plurality of images captured in the building site, select at least one image that comprises a view of a location of the object; select one or more classifiers from a plurality of classifiers in a classifier pool, for evaluating the at least one image, wherein said selection is based on an identity of the object, further based on a presumed degree of progress of the construction action as represented in the flow model, and further based on image parameters of the selected at least one image, wherein each of the classifiers in the classifier pool is configured to determine a state of progress of a construction action associated with an object based on an image, such that different classifiers in the classifier pool are designated to evaluate and classify a different combination of object, state of progress and image parameters; determine a current state of progress of the construction action based on processing the at least one image with the one or more classifiers; and control a route of a Site-Tracker monitoring device which is moved inside said building site and captures images for evaluating the state of the flow model, said route is determined and adjusted based on said determined current state of progress of the construction action, wherein said adjusting of said route is conducted to direct said Site-Tracker monitoring device so that one or more images of the presumed object location will be captured; wherein said one or more classifiers are members of a group consisting of: a decision tree, a Support Vector Machine (SVM), a Random Forest classifier, a Nearest Neighbor classifier and a neural network trained. a processor that operates, based on executing a set of instruction stored in a memory to: select an object for evaluation assigned to a construction action comprised in the flow model; from a plurality of images captured in the building site, select at least one image that comprises a view of a location of the object; select one or more classifiers from a plurality of classifiers in a classifier pool, for evaluating the at least one image, wherein said selection is based on an identity of the object, further based on a presumed degree of progress of the construction action as represented in the flow model, and further based on image parameters of the selected at least one image, wherein each of the classifiers in the classifier pool is configured to determine a state of progress of a construction action associated with an object based on an image, such that different classifiers in the classifier pool are designated to evaluate and classify a different combination of object, state of progress and image parameters; determine a current state of progress of the construction action based on processing the at least one image with the one or more classifiers; and control a route of a Site-Tracker monitoring device which is moved inside said building site and captures images for evaluating the state of the flow model, said route is determined and adjusted based on said determined current state of progress of the construction action, wherein said adjusting of said route is conducted to direct said Site-Tracker monitoring device so that one or more images of the presumed object location will be captured; wherein said one or more classifiers are members of a group consisting of: a decision tree, a Support Vector Machine (SVM), a Random Forest classifier, a Nearest Neighbor classifier and a neural network trained. <EOS>