Photogrammetry has great potential in animal ecology because it can be used to obtain measurements of animal features such as antler, horn, and body size from photographs in a remote, non-invasive fashion. Little use of photogrammetry has been made so far, however, mostly limited by the need to get sufficiently close to the target animal or have an object of known size in frame to scale it. Here, I aim to unleash the further potential of photogrammetry by validating it for measuring more complex traits using three-dimensional deer antlers for the first time. I calibrated and validated two different photogrammetric systems by measuring an object of known size in photographs from distances up to 200 meters. I then demonstrated the high accuracy of my photogrammetry in measuring a suite of antler features from dozens of roe and fallow deer antlers attached to skulls placed at various distances to emulate a free-living animal. I also developed and validated an efficient correction protocol to deal with curved and tilted antler features. My antler measurement estimates were characterised by mean errors lower than 5% when compared to true antler sizes, with my correction protocol for antlers particularly effective and validated with independent antler sizes. Most importantly, the ecological meaning of my antler estimates was not altered by my approach, because the ranking of the deer based on true antler sizes was identical to the ranking estimated by photogrammetry. My procedures can be followed to estimate highly precise and accurate antler sizes. As I was able to obtain highly precise and accurate measurements of deer antler features with photogrammetry, these techniques can be transferred to measure other complex traits (e.g., horn size) and body size in general (e.g., shoulder height). As photogrammetry is non-invasive, remote, and fast, it fits perfectly into modern wildlife conservation and management techniques. The technique is particularly suited to (but not limited to) the establishment of long-term studies that allow repeated measurements of individuals without the need to capture and handle them.