Detection of phenology using an improved shape model on time-series vegetation index in wheat

•Improved shape model is better in detecting growth stages when compared with previous methods.•ASD is better than UAV-DC and Greenseeker in detecting all growth stages except the tillering stage.•Simulated satellite index (EVI) from the MODIS has the best potential to detect all stages at large scales.•The accuracy of phenology detecting is highly related to the form and characteristics for the shape model.