1. A method for supporting low-level flights in which an obstacle warning is provided for the pilot, whereby information on topography of surrounding terrain is collected by at least one sensor located on an aircraft, whereby the information represents raw data, and whereby an image-like representation is calculated from the raw data, whereby the image-like representation comprises a pixel quantity with pixels P(i, j) in columns j and lines i, the method comprising: Calculating altitude values h(i, j) of the individual pixels P(i, j) in a geodetic coordinate system using flight condition data of the aircraft; Evaluating pixel quantity, whereby for each pixel P(i, j) the distance value is compared to a predetermined threshold value or threshold value range and the pixel P(i, j) is given an invalid status if a corresponding distance value is above the threshold value or outside a threshold value range; Defining in each pixel column j for each pixel P(i, j) of a reference altitude h ref with h ref =Min(h above , h below ), where h above is an altitude value of that pixel P(i′, j) with valid status in the respective pixel column j above measurement pixel P (i, j), which is nearest to the measurement pixel P(i, j) and h below is the altitude value of that pixel P(i″, j) with valid status in a respective pixel column j below the measurement pixel P(i, j) which is closest to the measurement pixel P(i, j); Evaluating the image-like representation, whereby the distance values of pixels P(i, j) adjacent within one column are compared in each pixel column j of the image-like representation from top to bottom or vice versa and the corresponding pixel P(i, j) is highlighted as a picture element if at least one of the following cases a) through c) is present: a) the condition (Rg i−1,j −Rg i,j )>dRg min and (Rg i+1,j −Rg i,j )>dRg min is fulfilled; b) the condition is fulfilled that pixel P(i−1,j) is invalid and (Rg i+1,j −Rg i,j )>dRg min ; c) the condition is fulfilled that the adjacent pixels P(i−1, j) above the measurement pixel P(i, j) and the adjacent pixels P(i+1, j) below the measurement pixel P(i, j) have an invalid status and the altitude value h(i, j) of the measurement pixel P(i, j) is greater than the reference altitude h ref , wherein the value dRg min is dependent on the resolution of the sensor used, Rg i, j is the distance value to the measurement pixel P(i, j) and Rg i−1, j and Rg i+1, j are the distance values of the directly adjacent pixels P(i−1, j) and P(i+1, j) in the column j of the distance image.