How to convert a Surpac generated model from local grid to National Grid Co-ordinates with NO Rotation

As a Geologist, the company you work with may acquire new mining tenements or plan to sell existing tenements. The models, the drillhole data and the string/wireframe data may all be in a local grid which is generally orthogonal to mineralisation and may need converting to the National Grid Coordinates.  In the next series of tips, we will cover: 

• Block Model Transformation with no rotation for GEOVIA Surpac generated models
• Database Transformation-Update Collars
• Wireframe/String Data Transformation
• Block Model Transformation with a rotation for GEOVIA Surpac generated models
• Block Model Transformation with no rotation for Datamine/Micromine/Vulcan/Minesight models.
• Block Model Transformation with rotation for Datamine/Micromine/Vulcan/Minesight models.

For the transformation of the data from the local/mine grid to the National Grid, you will need 2 points of reference/location that are the same for both grids. Remember, this article is for a transformation with NO rotation.

• Eg. Tenement Boundary Coordinates
  • Local Grid
    • Bottom Left:  North-7000, East 1200
    • Top Right: North 7600, East 2100
  • AMG Grid
    • Bottom Left: 6037000, East 1187200
    • Top Right: 6037600, East 1188100

• Open up the block model you want to transform from local grid to the national grid.
• Display block model
• Block Model>Export>Block Faces to DTM.

NOTE: We are doing this as we will use this information to create the new model. This step can be missed if you have the transformed coordinates.
 

• Block Model>Block Model>export>block centroids and dimensions to a string file.

• To convert the block model centroid file from local to national grid, File Tools> Transformations>2D transformation of a string file. Accept the adjustments and apply

• Repeat the same steps for the DTM of the block Model, but only use 2D Transformation of a DTM file. There is no need to transform the associated string file.

• Block Model>block model>New/Open

• Select the transformed shell to fill out the coordinates for the transformed block model. Remember to fill in the user block size. This is the parent cell size and can be obtained from the block model summary. Also, fill in the sub-blocking type and the size.

• Save the model.
• Display the transformed model and open up the transformed centroids. Make sure they align with each other.

• Next, we need to create the attributes in the block model. Depending on the version, you can use the method outlined in Geovia Surpac Tip - Saving Macros from the Block Model Audit Trail,​​​​​​​ which is located in the GEOVIA Community. Alternatively you can create the attributes by Block model>Attribute>New

• Block Model>block model>import>text file. 

• Remember, we are importing the transformed centroid string. If you have opened the file and saved it, MAKE sure you have saved it in a text format, not a binary format. For this example, our model has no subcelling, so we import the cells into the one block size. This step will vary depending on the model sub blocking type.

• Match the top up with the bottom. Remember, we are loading a string file, so y is in column 2. Note: If you can not read the data in the string file, it has been saved in a binary format. Open and resave in a text format.

• A report file will be produced so you can see what data has been loaded and what data has been rejected.

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