# Lissage¶

*Paleostress Trajectory Maps Based On The Results Of Local Determinations*

The Lissage program (Lee and Angelier, 1994) represents regional trends on 2-D gridded map (x-y plane) and can reconstruct a paleostress trajectory map by implementing the following two different methods (Lee and Angelier, 1993):

**1) Polynomial Method:**

Assume that trajectories of directional data are induced from a smooth directional field, so that a linear function is introduced to fit this directional field and a bivariate polynomial function for 2-D data in the x - y plane is used.

**2) Distance-weighted Method:**

Use an inverse distance-weighting averaging technique as an interpolation method, the local effects are considered in variable proportions as functions of the order of a power function.

Input Data & Compatibility

Lissage supports the following formats for input data:

- .csv (
*restriction*: seperator=’,’, decimal=’.’) - .xls
- .xlsx
- .shp

Input data should contain information for the first three of the following fields, at least:

Input-data | Explanation |
---|---|

‘x’ or ‘lon’ | geometric or geographic coordinate |

‘y’ or ‘lat’ | geometric or geographic coordinate |

‘azimuth’ | azimuth of horizontal stress axis direction, in degrees (0-360) |

‘theta’ | azimuth angular error range |

If input data is a flatfile (.csv, .xls, .xslx), user has to provide the program with the field names of longitude, latitude, azimuth and optionaly azimuth’s angular error.

Warning

If input data is a **flatfile**, Coordinate Reference System should be WGS‘84 (4326).
Output’s CRS would be WGS‘84 (4326).

Else, if input data has a vector format (.shp), user has to provide the program with the field name of azimuth values and optionaly azimuth’s angular error, as stated in the shapefile’s attribute table. There is no need to provide field names of longitude and latitude because these values are going to be sourced from geometry.

Warning

If input data has a **vector format**, Coordinate Reference System could be geometric
or geographic. Output’s CRS would be the same as input CRS.