Introduction

Background drawings are often used in conjunction with overlay drawing (interactive) and provide more visual, fine details.

This term also applies to scanned drawings.

In some cases a background drawing is misaligned or has other problems:

• it is not aligned with overlay

• it is not scaled correctly (measurements are off)

These issues can be easily fixed by using Move or Align functions.
First, make sure that you have sufficient privileges to perform this operation: a system version that you are working on must be in read/write mode, and you must have an edit right to the drawing.

Enter Edit mode and using a drawing list, select the background drawing that you want to fix.

Open

Match Drawing Viewport

In some cases a user will end up with drawings that are misaligned in some way:

• Drawing that was imported with "true north" parameters, so the building is positioned as in real world, but difficult to read. 
  Typically we would like to look at the building with an entrance at the bottom of the screen.

• Two drawings that do not match - e.g. an overlay drawing with a detailed background drawing. 
  In this case we would like to align one to another. 

Number of these issues can be fixed by Rotate and Match function in few simple steps. 

First, enter drawing edit mode and select a proper drawing that you want to work with. Then select Rotate and Match function on the Adjust toolbar:

Open

This operation can be applied to any part of the composite drawing. Please note that it does not apply to entire drawing (all parts) at once.

In this example we will Match Overlay drawing to background drawing that is positioned correctly. 

The Overlay Drawing is wrongly:

• rotated

• scaled

• positioned

Start the Rotate and Match function and follow the instructions. Select a first point of reference element: that is an distinctive element on the Overlay drawing that we want to change. 

For example, select a wall. You will match the same or corresponding element in the target position on a background drawing. 

The image below show a first step completed with a wall selected using a snap function on the source drawing:

Now add a second line representing target - where the first line (and drawing) should end up:

When ready, select the Accept button:

Drawing will be adjusted and reloaded. 

Re-adjusting or Resetting applied transformation

If the result is not correct there are two options as follows: You can re-adjust the drawing by simply repeating the operation once more or you can start with re-setting the stored transformation to none. 

To reset the transformation, please open Rotate and Match Drawing function and select Reset Viewport Transformation function:

Confirm the reset function and the drawing will be reverted to its original state:

Move Background Drawing

Move background function can be used when the drawing is scaled correctly but is wrongly located,

especially in relation to overlay drawing in the same document.

Click on the Move background button to enable this function and follow the instruction shown on the move drawing window toolbar.

Step 1: Select a source point on your background drawing, by clicking on it in the viewer window.

Step 2: Select a destination point. This is where a background drawing will be moved.

Verify if the move vector looks correct. Don't worry if it's not perfect, it might be easier to correct when both background

and overlay are almost correctly aligned. You can then see any offset easier and perform additional corrections.

The final result should look like this:

Align background drawing

Align function is more powerful than a simple move. It allows the following adjustments to be made depending on user needs:

• A drawing can be moved and scaled in one operation

• A drawing can be scaled to a known length element

Move and scale operation can be performed in case there is both misalignment and a size difference between background drawing and overlay.

Step 1: Make sure you are in Edit Drawing Mode. Select a background drawing from document selection combo

and choose Align Background Drawing function:

Step 2: Select a first point of the reference element, that is a point on a background drawing.

Then select a second point, creating a line. This line should represent a well-defined element in a drawing like a wall.

Step 3: In this case, we will choose an option to indicate a target line, that should represent the same element, for example, a wall, in overlay drawing.
After the second line is in place, verify the position of both lines and hit the accept button.

This will perform realignment of the drawing that now should match overlay. If the alignment is still off, start the function again and perform further corrections.

Both drawings are now aligned correctly:

Scale drawing by a known length element

This scenario is in most cases applicable to scanned drawings. If the measurements are off,

some of the scanned drawing parameters are not correct.

In some cases, an easy fix can be done by using a Composite Document Manager, where scanned drawing parameters can be set.

If your drawing had an original scale of 1:100, but the parameters are set to 1:1, the measurements will not be correct.

First, you can try setting a scale to an expected value. If that does not help, it might be the density that is set incorrectly, and that would be much harder to guess.

To simplify this, you can indicate an element on a drawing, e.g. a scale ruler that has a known length and provide that value to the system.

If there is no scale ruler on the drawing, you might try to measure a reference element in nature, like a wall or door opening, and provide the length of this element.

Step 1: Verify measurement on a drawing. Below we can clearly see that the measurement is off. Instead of getting 10 meters, we get a result of 16 meters. 

Step 2: Enter edit mode and select Align Background Drawing function. Draw the first reference line over a known element. 

Now you can see that the source and target length are the same and represent a wrong value.

Any of the parameters can be modified to obtain a correct measurement, but we will in this case enter known length:

A system suggested a scale that is slightly off. This might be because our reference line was not exactly spot on. 

You can neglect this difference or try to fine tune the calibration.