This section explains the meaning of the Custom Shape dimensions produced by the calculator, and provides step by step instructions for marking out your shape on-site based on these dimensions. When marking out the shape on-site you will need something to mark the key positions in the shape, and to mark the lines of the shape. You can use witches hats, pegs, and/or Landscape chalk and string to do this.
The screen shot above shows the calculated results for a custom shape, in this case a cross. As with the Rectangle shape, the dimensions of the outer border of the shape area are shown:
- Width across the front of the shape area - 12.4 metres
- Width across the back of the shape area - 39.2 metres
- The distance from the centre of the front row of the group to the exact centre of the group is 7.9 metres
- The distance from the exact centre of the group to the centre of the back row of the group is 25.9 metres
- Depth of the shape area measured at the centre line of the shape area is the sum of these last two figures 7.9 + 25.9 = 33.9 metres
In addition to the outer dimensions, GroupCalc divides the width and height of the shape area into eight (8) sections and gives the length of each segment when drawn on-site. When viewed from the camera these segments will appear to be the same size. Guide lines are included to assisting in marking out the shape onsite.
Below is a step by step explanation of how to use these measurements to mark out the shape on-site.
Step 1: Mark out the location of the camera and the outer border of the shape area
See Keystone Results for an explanation of how to mark out the outer border of the shape, and the location of the camera. The diagram below shows the results of following this procedure.
Step 2: Mark the segment heights along the centre line of the shape area
GroupCalc divides the height of the shape area into eight even segment (when viewed from the camera). When marked out on site the height segments get progressively higher towards the back of the shape. The height measurements provided by GroupCalc are measured along the centre line of the shape area, not the left or right side.
In this step we mark the height of each 1/8th height segment up the centre of the shape as shown in the following diagram.
If you are using GroupCalc Pro, then the heights of each eight segment as measured at the edge of the shape are also shown. You can mark these along the edge line of the shape as shown below. This assists in Step 3.
Step 3: Draw the horizontal lines between the eight height segments
Now that you have marked the boundaries between the height segments, mark a horizontal line through each mark extending to the edges of the shape area...
Step 4: Mark the segment widths at the front and back of the shape
Next you mark the widths of each of the 1/8 width segments across the front and back of the shape...
Step 5: Mark the "vertical" lines between the width segments
Now that you have marked the boundaries between the width segments, mark a "vertical" line through each mark extending from the marks on front of the shape area to the correstponding marks at the back of the shape area...
Step 6: Use the horizontal and vertical lines as a guide to draw your shape
Now that you have the guide lines in place you can use them to draw the outline of your shape...
When viewed through the camera you shape will look square in the frame.