In current era, characteristic by progress and technology development, we are witnessing a great improvement and refinement in the field of commercial unmanned aerial vehicles as well. Devices known as UAV, represents a new platform so called, “dron“ or remote controlled air systems, which are increasingly used in variety of data collection in forestry industry in the last decade. Thanks to their weight, construction, and the possibility of adaptation of variety of sensors, they have a wide range of deployment in different activities. The most common and the most used are devices, whose movement is perform by four rotary propellers, while there is vertical take-off and landing of a device. Another numerous group is represented by so called "wings": It is a specific group of devices which movement significantly differs from previous group. It works on a principle of buoyancy of a wing, whereby take-off takes place on the launch pad or throwing out of a hand. Detection of a heights of a predefined trees was performed by DJI Phantom 3 Professional and UX5 Trimble, which choice was based on selected preferences. Photographic flights took place on a same areas, while pictures made by UX5 Trimble were taken by a camera with a resolution of 16 megapixels. On the other hand pictures taken by DJI Phantom Professional reached a lower value with a resolution of 12 megapixels. We processed the obtained outputs using Agisoft PhotoScan Professional and ArcGis version 10.2. We compared these results with values measured by altimeter Vertex, determine the resulting differences and subsequently, to take account with the root mean squared error for DJI 3,3 m and UX5 2,6 m.