Quantitative spatial analysis of thermal infrared radiation temperature fields by the standard deviational ellipse method for the uniaxial loading of sandstone

•Quantitative studies on the infrared radiation temperature fields on rock surfaces caused by stress variations and fracture by standard deviational ellipse.•The inflection point on the curve of the ellipse parameters occurred earlier than that on the AIRT and standard deviation curves in the microfracture development stage.•In the fracture development stage, the area of the ellipse decreased, while the ellipticity increased. The shape of the ellipse changed from circular to striped.