Estimation and Simulation
Gridat provides main geostatistical Estimation methods like Ordinary Kriging, Lognormal Kriging and Indicator Kriging. Estimation Variance distribution models are available too.
Simulation methods, available at Gridat are Sequential Methods based on Ordinary, Lognormal and Indicator data.
Setting initial parameters for Estimation and Simulation are alike except for few parameters. Therefore how to use Gridat for both is referred here.
While your data sheet is activated , select "Kriging Estimation" for estimating models or select "Sequential Simulation" for simulating model from "Modeling" menu.
"Model Setting" window will be appeared.
Select the data columns you intended to use as X, Y, Z and W .
There is some initial statistical information about your data file here .
You may intend to use data collected from districted area.
Set your data limits here. Default values cover all data, recorded to the active data sheet .
You could reload default values by clicking refresh signs.
If you want to remove suspected data or highly suspected data from your process, check the appropriate checkbox here .
There is another tab labeled "Kriging". You can determine the initial settings for estimation or simulation there.
Select "Kriging" tab and see how you could determine initial parameters.
As you select "Kriging" tab, Gridat start to calculate homogeneity for the area you allocated at "Data" tab. Depended to your data file and your system capability, this may take a few minutes.
"Donít frighten. Gridat has done most of setting for you."
Gridat calculate the changes of varigram factors in the area through directions and draw a "Rose diagram" according to its calculations. Then recommend an ellipse (for 2D modeling) or an ellipsoid (for 3D modeling) for a homogeneity model of the area. This model shows parameters "a", "C0" and "C" via a 3D viewer object in the Homogeneity Ellipse/Ellipsoid area (Right side of the window) . Look at the ellipse/ellipsoid carefully. If the ellipse or ellipsoid does not obtain rose diagram (that is shown by gray lines)  you could change parameters of ellipse/ellipsoid. As you see parameters are diameters (a, b, c), Direction and Dip (for 3D models). Although you will not need to be worried about homogeneity if you are not intended to use homogeneity parameters as search area or Variogram parameters (as you know Kriging method based on Variogram parameters and data points collected from a specified search area).
Homogeneity models for Variograms parameters would not be involved in calculating if you leave the title "Obtain Homogeneity" at "Variogram Options" tab unchecked. In this case Gridat use a Variogram with the parameters determined at the proper boxes . Gridat calculates these parameters too. But you could change them. You could use parameters of an existing varigram model; you create it before, too. Just select the name of your Variogram model from "Get This Variogram" list and click on the title "Get This Variogram".
But if you check "Obtain Homogeneity" at "Variogram Options" tab, homogeneity models will be used as Variogram parameters for Kriging calculations.
The search area Kriging collect initial data from it would be determined at the tab titled "Search Options". Gridat uses greater "a" value as search radius. You could change it or you could order Gridat to use an ellipse or ellipsoid that obtains homogeneity model. Other search options related to your project specification and your geostatistical knowledge.
There is another tab here under the title of modeling area. You could determine the area you want to create the estimated or simulated model for. Donít mistake this area and the Data area youíve determined at "Data" tab . Try these options several times to understand how to use it.
Kriging method is selected by Gridat  according to your data normalization. But sometimes you may not agree with Gridat. In addition if you need to use indicator estimation or simulation methods, you must select "Indicator Kriging" here. Then always be aware about this option.
Donít forget as you change Kriging method, Gridat needs to create homogeneity again.
Refer to your geostatistical knowledge for other options, especially when Indicator Kriging is selected, because varigram settings are different there.
Now you are ready to view the result.
There is just something noticeable about 3D models. When you create 3D models there will be an extra figure near the "Grid Size". It determines the number of sections you want to create models at . In other words when you set the figures equal to 50x50x3, you order Gridat to create three models with 50x50 estimated or simulated points on it. These three models are alike at X; Y coordinates but different on elevation. The elevation for each section calculated by Gridat according to initial data Z column value. But you could change them. Click "Levels", double click the elevation you want to change, type your value and press "Enter".
Sections value is shown under the title of "Base Level" for 2D models. In this case the number of sections is 1 and the elevation is 0. You could shift up or down your modeling plate by changing the value of "Base Level". It sometimes is very useful.
Now click on the Ok.
Gridat needs time for calculation. If it takes too long, press F12 to cancel progress.
"Model Setting" window will be closed.
Now "Models" tab is activated and your model is created.
The title of the model is shown at the left side of "Models" tab, indexed by a number .
If you can't see it, select "Project Explorer" from "View" menu.
You can't change the index but the title of the map and other options could be edited.
There are several options for models available on "Property bar", at the right side of Model .
If you can't see it, select "Model Property Bar" from "View" menu.
Try several changes to being more familiar with this object.
For example you can indicate a special value range by defining a different color at the color palette .
All options are not available for every model. For example "CurrentLevel" property is available just for 3D estimated or simulated models. By changing this value you can view the model created at each level . To view all sections together you need to use "3D view" from "Tools" menu.
If you want to change some initial settings like data entry properties or Kriging parameters, right click the model and select "Option and Settings" to access "Model Setting" window again.
When you right click the model a popup menu will be appeared and some commands would be available. These commands are available at "Model Toolbar" too. If you can't see "Model Toolbar", select "Model Toolbar" from "View" menu. Try these commands to see how the model affected by each of them.
or contact me
Home Start with Gridat Data and GridatProject Create a Post map Statistical parameters Variography and Variograms Estimation and Simulation Gridat tools
Copyright ©2011 ampiroid. All Rights Reserved.