Low cost mapping using UAV technology is becoming a trendy topic. Many systems exist where a simple camera can be deployed to take images, generally georeferenced with a GPS chip and MEMS attitude sensors.<br> The step from using those images as information picture to photogrammetric products with geo-reference, such as digital terrain model (DTM) or orthophotos is not so big. New development in the field of image correlation allow matching rapidly and accurately images together, build a relative orientation of an image block, extract a DTM and produce orthoimage through a web server.<br>The following paper focuses on the photogrammetric performance of an ultra light UAV equipped with a compact 12Mpix camera combined with online data processes provided by Pix4D.<br> First, the step of image orientation is studied with the camera calibration step, thus the DTM extraction will be compared with conventional results from conventional photogrammetric software, new generation technique of pixel correlation and with reference data issued from high density laser scanning. The quality of orthoimage is presented in terms of quality and geometric accuracy.