At this time run the > Raster Calculator” selection that will display the window dialog in Figure 3. “Raster Fill in the dialog as indicated to produce the top contact elevation residuals grid. “top_resid” – Figure 4 displays the top contact grid residual in a gray-scale color scheme. Note that in the “top_resid” Results” window a left-click near the bedding data point yields a residual near zero at the “Identify outcrop point. Reclassify the Residuals The residual rasters will be reclassified so that values <= 0.0 are assigned a of 1, and values > 0.0 are assigned a value of 2. After this step both and will have the following “top_reclass” “bot_reclass” characteristics: Grid Node Value Reclassified Value < 0.0 1 (strata above contact exposed) >= 0.0 2 (strata below contact exposed) Find the SAGA Tools > Reclassify” tool in the Processing menu or Processing Toolbox window. “Raster Figure 5 contains the window dialog settings for reclassifying the to make the “top_resid” “top_reclass”. Make sure that you set the method to For minimum value you just need to set a value that is “Range”. guaranteed to be below the minimum residual value. The map is displayed in Figure 6. “top_reclass” Note that it consists of only two values, 1 for the outcrop of strata above the top contact surface, and 2 for strata below the contact. Add the Two Reclass Rasters This simplification will allow the top and bottom rasters to be together to produce a raster that “added” has the below characteristics: Top Grid + Bottom Grid = Composite Grid 1 1 2=younger strata exposed (strata above top and bottom contact) 2 1 3=intermediate strata exposed (strata below top contact, above bottom contact) 2 2 strata exposed (strata below top and bottom contact) Note that the condition of the top grid node = 1 and the bottom grid = 2 at the same map position is not possible if the top contact is structurally above the bottom contact. The composite grid separates the
At this time run the “Raster > Raster Calculator” selection that will display the window dialog in Figure 3. Fill in the dialog as indicated to produce the “top_resid” top contact – elevation residuals grid. Figure 4 displays the top contact grid residual “top_resid” in a gray-scale color scheme. Note that in the “Identify Results” window a left-click near the bedding data point yields a residual near zero at the outcrop point. Reclassify the Residuals The residual rasters will be reclassified so that values <= 0.0 are assigned a of 1, and values > 0.0 are assigned a value of 2. After this step both “top_reclass” and “bot_reclass” will have the following characteristics: Grid Node Value Reclassified Value < 0.0 1 (strata above contact exposed) >= 0.0 2 (strata below contact exposed) Find the SAGA “Raster Tools > Reclassify” tool in the Processing menu or Processing Toolbox window. Figure 5 contains the window dialog settings for reclassifying the “top_resid” to make the “top_reclass”. Make sure that you set the method to “Range”. For minimum value you just need to set a value that is guaranteed to be below the minimum residual value. The “top_reclass” map is displayed in Figure 6. Note that it consists of only two values, 1 for the outcrop of strata above the top contact surface, and 2 for strata below the contact. Add the Two Reclass Rasters This simplification will allow the top and bottom rasters to be “added” together to produce a raster that has the below characteristics: Top Grid + Bottom Grid = Composite Grid 1 1 2=younger strata exposed (strata above top and bottom contact) 2 1 3=intermediate strata exposed (strata below top contact, above bottom contact) 2 2 strata exposed (strata below top and bottom contact) Note that the condition of the top grid node = 1 and the bottom grid = 2 at the same map position is not possible if the top contact is structurally above the bottom contact. The composite grid separates the
OutcropPredictionExample_QGIS.docx