Modelling the Trestle

By

Pat Connelly

The most important thing for accurate modelling is taking front to back and side to side photographs.  They should be as straight on as possible with  little angling to keep the dimensions proportional. This picture is a high power view of the end of the trestle.  This is the spline editor and I have traced 1/2 of the trestle end as accurately as I can.   To keep symmetrical parts you should only model 1/2 the shape and then mirror the shape to get a perfectly symmetrical parts.  It is impossible to accurately trace both sides and end up with any sort of symmetry.

After saving the spline object, I then saved points as a typical imagine iob object.  The iob object can be loaded into the detail editor as displayed above.   I went into edit points mode and cleaned up the 1/2 outline as well as deleted the central line so all I have left is 1/2 of the outer outline in the next picture.  If you leave the center line your object will have a crack.

The center line is gone.  The axis has been repositioned so the z-axis is directly centered on the center of the object.  The axis repositioning is done while the center line is intact for accurate placement.  The object is mirrored across the x-axis and the two objects (left and right halves) are joined together.   Now you have a symmetrical faceless outline of the trestle end.  Faces needed to be added.

The end outline is extruded to 100 units (arbitrary amount).  In pick points mode the extruded end is selected and joined.  This effectively closes the end with faces.  The end point is then translated back 100 units on the y-axis to form the completed faced end.

The end is then extruded to the length of the trestle.  Somewhere, the object has to be scaled as the traced drawing is proportional but not to scale.   This was done prior to this last extrusion and before the faces were added.   The axis is placed on the corner of the object and it's z and x lengths are adjusted to match the object.  Then their absolute lengths are changed with the transform requestor.  My table is scaled to 1 inch = 10 imagine units.

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