Abstract: A system to automatically increment read-watermarks based on a set of predefined rules and criteria and configured to perform operations that include: accessing a message thread that comprises a plurality of messages; detecting a display of a message from among the plurality of messages at a client device, the message corresponding with an identification number from among a plurality of sequentially assigned identification numbers associated with the plurality of messages; applying the identification number that corresponds with the message from among the plurality of messages to a data object within a database associated with the message thread; the data object indicating a most recent message read by a user of the client device based on the identification number; detecting a trigger event; and automatically incrementing the identification number associated with the data object within the database responsive to the trigger event.

Abstract: A method for processing in a computer a plurality of digital images stored in the computer. The digital images are from respective photographs (301) of a geographic region. The photographs were taken from different directions. The method includes displaying the images (311) and upon selecting an image point in an oblique image, synchronizing a corresponding image point in the digital images so that the selected image point in the first image and the corresponding synchronized image point in other images have substantially identical world coordinates. The method is useful for performing a geographic measurement (319) on an oblique by selecting an image ground point below a first image point; calculating world coordinates in a vertical line segment which extends vertically from the image ground, and upon selecting the first image point on the vertical line segment, calculating world coordinates at the first image point based on the world coordinate in the vertical line segment.