That sort of thing can come from too low resolution, blurry images (out of focus / camera shake), and also from lens distortion.
1. What sort of camera are you shooting with?
2. Are you using a tripod?
3. Have you already tried calibrating your camera using Agisoft Lens?
You'll also probably want to retopo the model and reproject the textures before using it in any serious realtime project, btw.