Orbit ephemeris and camera data are needed for strict geometric rectification of linear array push-broomimagery

which are often unavailable in practical applications. As a result

the direct linear transform （DLT）

averagepolynomial

improved polynomial and rational function model （RFM） methods are widely used for the approximate geo-metric rectification of this kind of imagery. In this paper

after a brief introduction of several approximate rectification al-gorithms

the emphasis is put on experimental analysis and precision comparison of different kinds of approximate rectifi-cation algorithms using real SPOT and IKONOS images. Experimental results show that the precision of RFM method isthe best and can reach sub-pixel accuracy

the precision of DLT method is about two pixels on the condition of good dis-tribution of control points

the precision of average polynomial method is about one pixel for fiat terrain and much worse foruneven terrain

i. e.

varying greatly with different kinds of terrains

and the precision of improved polynomial methodsvaries with the order of polynomials and is nearly irrelative to the types of terrains. If the proper improved polynomialmethod is selected for image rectification

the higher precision can be obtained. Additionally

the balance among preci-sion

complexity

requirements for known data should also be considered for choosing methods from these four approxi-mate image rectification algorithms. Experimental results also show that the improved polynomial method is a better choicefor approximate rectification of linear array push-broom imagery

from the viewpoints of precision

complexity

the num-ber and spatial distribution of control-points and so on.