—— PN M); - ve 
dae 7€ ND NM M 
  
  
289 
3.2 Steel industry: Digitization of steel ladles 
The measurement of these red-hot steel transport containers with temperatures of up to 1000° C can only be performed 
in a contact-free, on-site measuring process. The large dimensions of the conical ladies with a diameter of 3.8 m and a 
depth of 4 m necessitate the use of the large-format, high-resolution UMK-SCAN digital camera. Due to the extreme 
heat, the distance between the camera and the ladle must not be any less than 7 m, as otherwise the temperatures on 
the camera lens would reach critical values. The ladie must not take any longer than 20 minutes for the measurement, 
otherwise it would cool down too much and its temperature would fall below the specific level required for the next load 
of steel. The user specified that 45 minutes should be the maximum time allowed for obtaining information as to whether 
the ladle could continue to be loaded with steel or whether the wear of the fireclay called for reconstruction (at a cost of 
approx. £ 25,000). This decision is made on the basis of comparisons with a reference ladle and DEMs of earlier loading 
conditions. The SCOP program for isoline computation (INPHO Stuttgart, Technical University of Vienna) was used for 
this purpose. 
  
InduSURF Digital - Measurement of ladles on site 
  
Task: Digitization of the interiors of red-hot steel ladles : 
QO DEM of the ladle walls and bottoms with a point density of approx. 5 cm, accuracies < + 10 mm 
OU Comparison with a reference ladle and DEMs obtained in earlier measurements of the ladle 
C] Information as to whether the ladle is OK after no more than 45 minutes 
  
Parameters Ladle - Recording and plotting 
  
Sensor used UMK-SCAN, ck = 100 mm 
Number of images 2 images (1 model) 
Data quantity 50 MBytes 
Defined points on the object 
Recording time 
Measurement and orientation 
Point accuracy 
4 retro-targets on the ladle edge, 10 points in the vicinity 
2 minutes 
10 minutes 
Sx/z  bmm, Sy2 8mm 
  
  
InduSURF SGI computer 
Point number in DEM 
Computation time 
Mean elevation error 
  
Indigo, 100 MHz, 32 MB RAM 
approx. 5000 points (5 cm grid) 
30 minutes 
Sy = +8 mm 
  
  
Table 3: Results of one ladle measurement 
  
  
  
Fig. 5: Digital image of a ladle Fig. 6: 3D point cluster for plotting 
IASPRS, Vol. 30, Part 5W1, ISPRS Intercommission Workshop "From Pixels to Sequences", Zurich, March 22-24 1995