Method of detecting data relating to thermal energy radiated in a scene covering a control volume to be monitored using infrared radiation image processing, said method comprising the steps of: receiving a sequential plurality of infrared radiation images of the scene, each of said images comprising an array of pixels, each pixel having a value which is representative of a pixel's fraction of the infrared radiation intensity associated with the array of the image; processing successive images of said sequential plurality of images in order to determine a change in at least one thermal parameter that meets predetermined alarm criteria; and detecting an event in the scene based on the change determined in the thermal parameter; characterized in that said sequential plurality of images consists of at least two sequential series of images simultaneously detected from respective different points of sight (TC1, TC2) arranged in a predetermined geometrical relationship with respect to each other, wherein said processing step comprises the steps of: associating sub-areas of the arrays of the images (I1, I2) with volume sectors of the scene, the position of which within the scene can be determined depending on the positions of the sub-areas within the respective arrays of the images detected from the different points of sight and on the geometrical relationship between the points of sight from which said sequential series of images are detected; and calculating said at least one thermal parameter for each of the volume sectors of the scene from the pixel values of the sub-areas of the arrays of the images, depending on the position of each of the volume sectors with respect to said points of sight. receiving a sequential plurality of infrared radiation images of the scene, each of said images comprising an array of pixels, each pixel having a value which is representative of a pixel's fraction of the infrared radiation intensity associated with the array of the image; processing successive images of said sequential plurality of images in order to determine a change in at least one thermal parameter that meets predetermined alarm criteria; and detecting an event in the scene based on the change determined in the thermal parameter; characterized in that said sequential plurality of images consists of at least two sequential series of images simultaneously detected from respective different points of sight (TC1, TC2) arranged in a predetermined geometrical relationship with respect to each other, wherein said processing step comprises the steps of: associating sub-areas of the arrays of the images (I1, I2) with volume sectors of the scene, the position of which within the scene can be determined depending on the positions of the sub-areas within the respective arrays of the images detected from the different points of sight and on the geometrical relationship between the points of sight from which said sequential series of images are detected; and calculating said at least one thermal parameter for each of the volume sectors of the scene from the pixel values of the sub-areas of the arrays of the images, depending on the position of each of the volume sectors with respect to said points of sight. associating sub-areas of the arrays of the images (I1, I2) with volume sectors of the scene, the position of which within the scene can be determined depending on the positions of the sub-areas within the respective arrays of the images detected from the different points of sight and on the geometrical relationship between the points of sight from which said sequential series of images are detected; and calculating said at least one thermal parameter for each of the volume sectors of the scene from the pixel values of the sub-areas of the arrays of the images, depending on the position of each of the volume sectors with respect to said points of sight.