Operation process
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Sampling survey to the total area of the forest of Heshun county in Shanxi province in year 2000 |
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Step 1: Prepare the raster data of the sampling zone, then enter the spatial sampling interface: |
Figure 1.Select the sampling steps |
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Step 2: Select the sampling model |
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Figure 2.Select the layer file |
Click “Preview Stratified Plot”, then preview the layer, in the figure, the color amount is the layer size, which is relevant to the imported layer file, from the figure 4, we can see that there are 5 layers. |
Figure3. Preview the s tratified p lot |
Step 3: Set sampling parameters |
Figure4.Set the sampling parameters |
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Figure5. Calculate the sample size (In the left graph, total cost-sample size is gained by computing the formula, in the right graph, the cost is the sum of the base cost and the product, which is that the cost per sampling unit multiply sample size)
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Step 4: Browse the sampling sites
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Figure6. Feature table of the sampling sites |
In Figure 6, the two columns in the table ( SmID 、 SmUserID) are automatically created by Supermap, the first column is the internal order of the data record, the second column is the order that signify the record by user, which can be modified according to the requirement, X 、 Y is latitude and longitude of the sampling sites, Bvalue1 Bvalue2 Bvalue3 are the different wave of the image, the value is the grey level of this sample site in these waves, “Value” is the investigated forest area of this sample site, which need to inputted by user. |
Figure 7.Sampling site distribution |
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Step 5: Close the opened data source, open the sampling wizard dialog, click and open the existed sampling file, open the new sampling design in the place of sampling design, namely, .spj file defined by user. |
Figure8. Open a existed sampling file |
Step 6: Input the sample site data. In Figure 9, Bvalue1 Bvalue2 Bvalue3 are the different waves of the image, the value is the grey level of this sample site in these waves, “Value” is the forest area of the sample, LayerID is the layer number. |
Figure9.Input the data |
Select the sample values, there are two input ways, user can input by hand or import from the file, and input the confidence level. |
User can select the other statistical inference models according to the requirement. |
Step 7: View the calculation results. |
Figure10. Scatter plot ( X-axis is the sampling unit size, Y- axis is the forest area of each sample unit) |
Calculation is completed. (Because the sampling sites are generated randomly each time, and the change of each sample site is larger, the screenshots results and the calculation results may be not complete agreement) |
Figure11. Result report of the statistical inference |
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Note: Before creating the new project file or importing the existed one, user need to close the opened project file. |
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