A method comprising: displaying, via a display screen of a user interface of a computer system, an image representing at least a portion of a structure, wherein a plurality of data sources is located in the portion of the structure, each of the data sources providing a value of a parameter associated with a zone of the portion of the structure; displaying, via the display screen of the user interface, a gradient indicator representing the parameter associated with the zone of the structure, wherein the gradient indicator is displayed with the image in accordance with the zone for the parameter; characterized in that the gradient indicator is generated by: creating a reduced-scale bitmap that is proportional to a viewable display area of the image but of a reduced size, generating a polygon for each of the data sources by tessellation of the portion of the structure, wherein the polygon comprises a graphical indicator, wherein a value of the graphical indicator is selected based on the value of the corresponding data source, drawing the polygons into the reduced-scale bitmap and filling each polygon with the respectively selected value of the graphical indicator, and, subsequently, stretching the reduced-scale bitmap to an increased size to draw it into the viewable display area of the image in accordance with a resolution of the display screen, thereby creating a gradient in the graphical indicator of the polygons. displaying, via a display screen of a user interface of a computer system, an image representing at least a portion of a structure, wherein a plurality of data sources is located in the portion of the structure, each of the data sources providing a value of a parameter associated with a zone of the portion of the structure; displaying, via the display screen of the user interface, a gradient indicator representing the parameter associated with the zone of the structure, wherein the gradient indicator is displayed with the image in accordance with the zone for the parameter; characterized in that the gradient indicator is generated by: creating a reduced-scale bitmap that is proportional to a viewable display area of the image but of a reduced size, generating a polygon for each of the data sources by tessellation of the portion of the structure, wherein the polygon comprises a graphical indicator, wherein a value of the graphical indicator is selected based on the value of the corresponding data source, drawing the polygons into the reduced-scale bitmap and filling each polygon with the respectively selected value of the graphical indicator, and, subsequently, stretching the reduced-scale bitmap to an increased size to draw it into the viewable display area of the image in accordance with a resolution of the display screen, thereby creating a gradient in the graphical indicator of the polygons. creating a reduced-scale bitmap that is proportional to a viewable display area of the image but of a reduced size, generating a polygon for each of the data sources by tessellation of the portion of the structure, wherein the polygon comprises a graphical indicator, wherein a value of the graphical indicator is selected based on the value of the corresponding data source, drawing the polygons into the reduced-scale bitmap and filling each polygon with the respectively selected value of the graphical indicator, and, subsequently, stretching the reduced-scale bitmap to an increased size to draw it into the viewable display area of the image in accordance with a resolution of the display screen, thereby creating a gradient in the graphical indicator of the polygons.