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Creating a Color Model from GPR (Ground Penetrating Radar) Profile Images

Table of Contents Table of Figures .................................................................................................................................................................1 Introduction .......................................................................................................................................................................1 Step 1: Gather the Images ...................................................................................................................................................2 Step 2: Display the GPR Panels in 3D ..................................................................................................................................2 Step 3: Extract Pixel Colors and Interpolate the Color Model .................................................................................................3 Step 4: Filter the Color Model .............................................................................................................................................4 Step 5: Append the Original GPR Panels ..............................................................................................................................4 

Table of Figures Figure 1: Sample GPR images ............................................................................................................................................2 Figure 2: Image File Names and Coordinates in the RockWorks Utilities Datasheet .................................................................2 Figure 3: GPR Images Displayed as Vertical Panels in RockPlot3D ........................................................................................3 Figure 4: Example of Image Pixel-Sampling for Color Modeling ............................................................................................3 Figure 5: 3D Voxel Display of a Solid Color Model ..............................................................................................................4 Figure 6: Color Model Filter Settings ...................................................................................................................................4 Figure 7: Color Model Filtered for a Color Range, with Source Images ...................................................................................5 Figure 8: Color Model and Image Panel with Vertical Exaggeration........................................................................................5 

Introduction This case study shows how images can be used to create a color model. The input images represent Ground Penetrating Radar (GPR) profiles, which can be displayed in 3D in RockWorks, as well as interpolated into a solid color model. Specific colors can be displayed, and their volume represented.

Once a color model is created, it can be displayed as a 3D voxel diagram, sliced in 3D fence panels, 2D profiles and cross-sections, 2D plan views, etc.

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Step 1: Gather the Images We start with five bitmaps that represent GPR profiles as shown below. These profiles were interpreted (aka "doctored") within a paint program to highlight salient features (e.g. a zone of stratigraphic disturbance associated with a buried object).

Figure 1: Sample GPR images

Step 2: Display the GPR Panels in 3D The image names and corner-point coordinates were then stored with the RockWare Utilities datasheet as shown below.

Figure 2: Image File Names and Coordinates in the RockWorks Utilities Datasheet

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The Imagery / Vertical Images -> 3-D Panels program was then used to display the images in three-dimensions.

Figure 3: GPR Images Displayed as Vertical Panels in RockPlot3D

Step 3: Extract Pixel Colors and Interpolate the Color Model The Imagery / Vertical Images -> X/Y/Z/Color program was then used to convert selected pixels within the GPR images to control points (see diagram below). This program also plots the extracted control points as color-coded spheres. Note: This step is typically unnecessary when creating a model (since the modeling also performs the necessary image-to-control-point extraction). It has been included here in order to illustrate the relationship between the control points and the original imagery.

Figure 4: Example of Image Pixel-Sampling for Color Modeling

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Next, the Imagery / Vertical Images -> Color Model program was used to create a solid model by using a anisotropic inverse-distance algorithm. The model can be displayed in RockPlot3D as an all-voxel display.

Figure 5: 3D Voxel Display of a Solid Color Model

Step 4: Filter the Color Model The next step was to set the model filter to the color of interest (yellow) and view the disturbed region (below). Note the volume (19 million cubic meters) represented by the yellow region.

Figure 6: Color Model Filter Settings

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Step 5: Append the Original GPR Panels Next, the original GPR profile diagram was appended to the 3D view of the filtered model. In the diagram below, the western panel has been hidden and the panel opacity has been set to 40%.

Figure 7: Color Model Filtered for a Color Range, with Source Images

The diagram below depicts the northern GPR image and the "disturbed" portion of the model at a 3x vertical exaggeration.

Figure 8: Color Model and Image Panel with Vertical Exaggeration