1. A method comprising: accessing a plurality of images, each image of the plurality being associated with geographic location information and direction information identifying a view point of a camera that captured the image; identifying a portal in an image of the plurality of images, wherein the portal is associated with a point of interest identified by a location of a map marker in map data; accessing surface depth data identifying one or more distances from the geographic location of the camera that captured the image to objects of the image; determining a distance from the camera that captured the image to the portal in the image based on the surface depth data; determining, by a processor, an approximate geographic location of the portal based on the determined distance and the geographic location information and direction information associated with the image; and using the approximate geographic location of the portal to adjust the location of the map marker in the map data.