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Showing Tomography

The tomographic 3D image of the core is composed of 3D pixels ("voxels"), each representing the X-ray attenuating power (attenuation) of the material at that point in space. The attenuation depends on the density and mean atomic weight of the material. Higher density and higher atomic weight both correspond to higher attenuation.

Materials rich in heavier elements, such as massive sulfides or galena, are more impenetrable to X-rays and have a higher attenuation value, while lighter materials like quartz have a lower attenuation value.

Compare this to medical X-ray imaging, where bone lets through less X-rays than the surrounding soft tissue:

Medical vs Rock

The left picture shows highly attenuating bone in a hand highlighted in white. To the right is the Preview area of Orexplore Insight showing a highly attenuating galena intercept highlighted in red/orange, along with its corresponding increase in lead concentration and overall rock density.

The 3D Tomography View

The tomographic Preview shows a low resolution down hole preview of the entire drill core. To bring up a segment of core for closer inspection at full (200 μm per voxel) resolution, begin by switching to the the 3D Tomography view:

3D Tomography

Selecting a Segment

To bring up a segment in the 3D Tomography view:

  1. Pick the Select Segment tool from the toolbar:

    Select Segment Tool

  2. Click and drag across the desired segment in the Preview area:

    Selecting Segment

    Upon releasing the mouse button, the selected segment is shown in the 3D Tomography view. The blue selection highlight in the Preview area indicates the currently selected segment.

Note

The amount of core that can be shown in the full resolution 3D Tomography view is restricted to roughly 10 cm at a time. If while dragging, your selection exceeds this limit, the blue selection highlight turns pale and the 3D Tomography will show the message Selection too large to display. The segment concentration summary table will still be updated to reflect the selected segment.

Controlling the Camera

The dip and direction of the camera in the 3D Tomography view can be controlled by dragging the mouse inside the view with the left button held down. The view can also be zoomed using either the scroll wheel, two finger scrolling or by dragging the mouse with the right button held down.

Working with Bookmarks

If you have found a segment of core you wish to save and easily find your way back to, you can add a bookmark:

  1. Select the segment you wish to bookmark and pick Project → Add Bookmark... from the menu bar:

    Add Bookmark

  2. Enter a name and optionally a description for the bookmark and confirm with OK :

    Bookmark Name

  3. Later, you can go back to the same spot by picking the bookmark under Project → Go to Bookmark in the menu bar.

Caution

The bookmarks are saved as part of the project file; remember to always save your project, to avoid losing your bookmarks.

Clipping

When viewing the full tomography, it may be the case that different parts of the volume overlap, obstruct and/or obfuscate each other, in particular when dealing with massive phases that render as nearly opaque.

Clipping allows to selectively hide parts of the volume, to better reveal others:

Clipping

Clipping is performed with a clipping plane, that separates the volume into a hidden and a shown half. The clipping plane is enabled by clicking Show → Clipping in the menu bar:

Enable Clipping

The clipping plane is defined by a surface normal, which may be moved along the plane by clicking and dragging its center point:

Move Normal

The plane itself can be moved by clicking it and dragging it along the surface normal:

Move Plane

The plane and the surface normal may also be rotated into a preferred orientation, by clicking and dragging the end point of the normal:

Rotate Normal

Saving Images

To save the current segment of core as a PNG image, pick Hole → Save 3D Tomography View to PNG... from the menu bar:

Save Screenshot

In the appearing window, choose some parameters for the image:

Save Screenshot

When confirming using the Save button, you will be asked to provide an output file name. If you just want to copy the image to the clipboard, click the Copy to Clipboard button instead.