AT_2D |

**Overview**

AT_2D is a class specially designed to handle Aerial Triangulation (AT) computation of a two-dimensional block. The mathematic models used in the adjustment and can be selected by the user are conformal (4 parameters), affine (6 parameters) and 2nd order polynomial (10 parameters).

The unit measurement of ground control coordinates and photo coordinates can be different and can be of any kinds of units. It will be taken care of by a scale factor parameter in the mathematic model. In other words, the scale factor coming out as a result of an adjustment has already absorbed the scale difference due to unit difference. The mathematic model does not have any knowledge of them, though.

In practice, it is not common that a block adjustment can achieve a good result at the first run, due to human error and large amount of data. There will be always some editing in data files, and it can be done very easy in Noobeed, by putting a slash sign, "/", in front of a record to turn them into a comment record. Individual standard deviation can be always put at the end of an observation at will, though a default value is given when omitted. The results from an adjustment are neat and easy to understand.

**Member data**

Name | Data type | Meaning |

sd_gcp | double | standard deviation of ground control coordinate |

sd_xpyp | double | standard deviation of photo / image rectangular coordinate |

**Operator**

no operator provided

**Construction function**

*
{AT_2D**}*
ret = AT_2D()

Example:

->block_1 = AT_2D() |

**Lfunction**

object.SD_GCP() ={double}left-value

object.SD_XPYP() ={double}left-value

Example:

->block_1.sd_gcp() =
0.50
->block_1.sd_xpyp() = 0.030 |

**Class function**

ADJUST | LOADGCP | LOADOBS | SD_GCP | SD_XPYP |