Validate an infolayer with another layer as a reference layer
This page describes how to use the Validation window, used as tool to analyse grids and images.
See below a how to for each type:
See also:
- Image Classification
- Rectangular Grid Generation
Thematic or classified image validation:
- select an infolayer to be validated, clicking on the "Validation..." button, this infolayer must have the image representation
- select an infolayer to be used as a reference, clicking on the "Reference..." button, this infolayer must have point or image representation
- select the "Sampling Rate", if the reference layer has an image as representation *
- associate the similar classes, if the layers belongs to different Categories
- associate classes, selecting both and clicking on the button "Associate"
- dessociate classes, select an existing association from the list and clicking on the "Dessociate" button
- do the validation, clicking on button "Execute"
- when the validation is done, the following windows will be show:
- Report, showing both the validation and reference layers, the number of computed samples, sampling factor, error rate and kappa index *
- Graph, showing a graph with Error Histogram for each class on the reference layer
* Sampling rate: defines an interval, in pixels, defines a rate with the samples will be taken. If sa = t5, this means that for each 5 lines and columns (a 5x5 pixels region), a pixel will be taken as a sample for the validation;
* Kappa index: is a statistical measure of inter-rater agreement for qualitative (categorical) items. The kappa index has the following agreement table:
Kappa Index |
Agreement |
< 0 |
No agreement |
0.00 a 0.19 |
Poor |
0.20 a 0.39 |
Weak |
0.40 a 0.59 |
Moderate |
0.60 a 0.79 |
Strong |
0.80 a 1.00 |
Excellent |
Kappa index calculation example:

Example: Classified image validation:
The following picture shows a Validation window example.
The following picture shows a Report window example.
The following picture shows a Graph window example.
Regular grid validation:
- select the layer to be validated, clicking on the "Validation..." button, this layer must have a grid representation
- select a layer to be used as reference, clicking on the "Reference..." button, this layer must have sample points or a grid
- select the "Sampling Rate", if the reference layer has an grid as representation *
- do the validation, clicking on button "Execute"
- when the validation is done, the following windows will be show:
- Report, showing the validation and reference layers, the sampling factor and some statiscal values in respect to error
- Graph, showing three graphics, Error Spatial Distribution, Error Histogram and Observated x Estimated Diagram
Exemplo Validação de Grades:
The following picture shows a Validation window example.
The following picture shows a Report window example.
The following picture shows some Graph window examples.