Common commands

CorrMap provide the Home section shown in Fig. BO.13 which contains commands and utilities that you can use in all CorrMap transformations. You can open this section at any time while you are performing a transformation by simply clicking the Home option in CorrMap main menu. For greater clarity the commands of the Home section are grouped into boxes explained below.


Fig. BO.13 – CorrMap Home section contains commands and utilities that you can use in all CorrMap transformations.


image393This command deletes the objects currently selected in CorrMap's graphic area (points, lines, etc.). The objects are removed from the raster map and, if they have corresponding numerical data in CorrMap Output window tables, they are also deleted from these tables.

image394Clicking this button you activate the selection mode. The cursor becomes an arrow and you can select any object in CorrMap's graphic area, such as points, lines, etc. When you select an object, the color of this object changes to indicate that it has been selected. For example, if you select a point, it becomes red (from blue or green). The selection can be used in combination with the Snap command described in the Query paragraph below. Select all selects all the entities on the program graphic area (points, texts, etc..) and can be useful, for example, when you want to delete all things that you added to the original raster in one operation. Unselect deselects all selected entities.



This command can also be activated by clicking the mouse wheel in CorrMap's graphic area. Once you have activated it, the cursor becomes a hand. This means that from that point you can move the image (without changing the zoom factor),  allowing you to browse the map. To do this, simply click and hold the left mouse button and drag the cursor. Clicking the mouse wheel again, the command is disabled and the cursor returns to its original shape.

image399 This is the classic zoom window that allows you to zoom in to a frame you trace with the mouse.  Once you have activated it, the cursor turns into a magnifying glass (with the symbol +), to zoom the desired area, just click on the first vertex of the box you want, hold down the mouse button and trace the zooming box.

image398 These are the usual commands to increase / decrease the current zoom factor. Zooming can also be activated dynamically by rotating the mouse wheel.

image400 The zoom factor is reset so that the entire image is contained in CorrMap's graphic area.

image401 Indicates the value of the current magnification. Clicking the down arrow to the right of the cell, you can open the list of magnification factors (150, 125, 100, 75, 50, etc..) and select one of them to get the image zoom accordingly.

image402 By activating this command the cursor changes to a cross. If you then click and hold the left mouse button the program brings up a circle of magnification that allows you to be more precise while clicking points on the map.



Fig. BO.14 – CorrMap's magnifying glass.


image404 Points dimension

The points you insert in your CorrMap transformations are drawn on the map as an X symbol of different color (depending on the type of point: reference, grid, control, tracing, etc.). During your transformation operations it might happen that these symbols are too big and may obscure the map. In Fig. BO.15, for example, some points indicated with a dark red X (tracing points) are very close together so that the symbols  can be confusing. To avoid this problem, CorrMap provides two useful commands that allow you to shrink or enlarge the point symbols depending on your needs. These two commands are represented by the two buttons X+ and X- in CorrMap toolbar. Clicking them you get the reduction or enlargement of the symbols. For example, clicking the X- button a few times in the transformation shown in Fig. BO.15, the X symbols of the points are reduced as in Fig. BO.16, thus obtaining a clearer view of the map. Of course you might need to do the opposite, i.e. enlarge the symbols, for example when you zoom very close some symbols may become too small.



Fig. BO.15 – CorrMap lets you increase or decrease the point symbols ....



Fig. BO.16 – .... for a more clear view of the map.

Move point

This command allows you to move a point already inserted on the map. It is very useful when you need to correct the position of a point that you placed incorrectly or not accurate enough. Once you have activated the command, you get the help window of Fig. BO.17 showing the instructions on how continue.



Fig. BO.17 – The Move point command allows you to correct an incorrectly positioned point on the map.

Import XY2 points

Other than the formats described in section Basic Operations | Export and Print, CorrMap provides a useful utility to export the transformations data to a normal CSV (comma separated values) text file, giving it the .XY2 extension. The meaning of this extension is that this file contains a pair of X-Y coordinates:

1.the raster coordinates;

2.the absolute-map or the real-survey coordinates.

This file is useful when you want to exchange the data between two transformations or you want to send this data to another CorrMap user. To export this file, once you have inserted the point of a transformation, select the row of one point in the Reference points or Transforming points tables in CorrMap Output window, then activate the Export .XY2 option from the right click context menu, as shown in Fig. BO.18 (related to the Reference points of the Affine transformation described in section Transformations | Affine). The Windows dialog box for saving a file is opened and you can then save the exported file. The file name suggested by the program is the same as the original raster with the following suffixes: .RIF for reference points; .INQ for control points; .TRA for tracing points; .DET for both control and tracing points together. Please refer to the chapters of the Transformations section for the explanation on these categories of points.


Fig. BO.19 – CorrMap allows you to export/import the points data of the transformations.

The .XY2 file exported for the example of Fig. BO.18 is as follows:










The letter 'R' as the last data means that the point is a Reference point. For the other types of points this letter can also be 'T' (Tracing points) and 'C' (Control points).

So, when you start a new CorrMap project as explained in section Basic Operations[****]|[****]Starting a new project and you want to import the points previously exported from another transformation, go to the corresponding table of the Output window and activate the Import XY2 points from CorrMap Home section. Select the .XY2 file and you get all the points inserted in the table and drawn in the map.

Guide lines

The main purpose of CorrMap is to retrieve the coordinates of map points in order to use them in topographical projects. To do this you need to click the points you are interested in, as explained in the chapters of section Transformations. This operation is of course made easier by the zoom commands described above in this section. However, in certain situations the zoom commands are not sufficient to exactly identify a point. This happens, for example, when the point is at the intersection between two or more map lines because if you zoom in very closely you lose the direction of the lines, you only see the mass of pixels forming the line junctions and you are no longer able to estimate the best intersection point. Another case is when you need to select continuous lines that present very slight deviations that are difficult to detect. Also in this case, if you zoom in too closely you lose the direction of the lines and you're no longer able to perceive the deviation.


To overcome these difficulties, CorrMap provides the Line command that allows you to draw vector lines on the raster map. These vector lines can then be used during the transformations to select vertices using the Snap mode, thus obtaining the maximum precision.

We explain the functionality of the  Line command by means of an example. So let's start a new CorrMap project as explained in section Basic Operations[****]|[****]Starting a new project and select the MAP5.JPG file from the CorrMap samples folder (see section Getting started | Samples and demo version). The map will be opened in CorrMap, we then select the Home section in the menu on top as shown in Fig. BO.19 (1) and locate on the map the boundary lines between plots 5550 and 5660 (near the word "Forcola"). These lines, in fact, have some very slight changes of direction which are difficult to identify.



Fig. BO.19 – CorrMap allows you to export/import the points data of the transformations.

To avoid selection errors, we then activate the Line command (2 in Fig. BO.19) and start drawing a guide line from the South-West vertex of plot 5660 indicated by a red circle in Fig. BO.19. So, let's zoom in this point and click on it. Doing so, we'll see that an elastic line is drawn following the mouse, as shown in Fig. BO.20.



Fig. BO.20 – Tracing a guide line useful to select map points at the maximum precision.


We now need to maintain the zoom factor but, at the same time, we need to move the map to reach the next vertex in North-East direction. To do this, we simply press the mouse wheel, the cursor turns into a hand and, as long as it remains this shape, we can click the left mouse button, keep it held and drag the raster in the desired direction. This is the Pan command explained in the Tools paragraph of this section.

If we also need to zoom in during these movements, we can do it by turning the mouse wheel, being aware that this disables the Pan (hand-cursor) which should be then reactivated if necessary by pressing the wheel again. In this way we can evaluate even the minimal directional changes of the map line, using a wider zoom, then select the vertices with higher magnification on the point, as shown in Fig. BO.21 and Fig. BO.22.



Fig. BO.21 – Firstly use a wider zoom to locate the line fold ....


Fig. BO.22 – .. then use a closer zoom to select the folding point.

Once we have traced the line between the first two vertices, the  Line command remains active to let us continue tracking the adjoining line. This line can now hook to the final vertex of the first line. To do so, we just need to activate the Lines snap command in CorrMap toolbar (3 in Fig. BO.19). With this setting enabled, we can now select the end of the line just drawn so that the new line will start exactly from this point, as shown in Fig. BO.23.



Fig. BO.23 – How to select the previously traced line vertices using the Snap.

The Lines snap command also allows you to easily delete a guide line. To do so, with the Lines snap activated, you select a guide line by clicking one of its two vertices and, when the snap little red square appears, you can delete the line by clicking the Clear button on CorrMap's Home toolbar, described in the Tools paragraph above.

If the operations described are not sufficient to exactly detect a very slight deviation of map lines, there's another utility offered by CorrMap to solve the problem. For example, let's consider in the same map the line dividing the plots 4648 and 4649  (just at the bottom-left of the area above). As you can see in the top half of Fig. BO.24 this line has a very slight deviation at the point indicated by the red circle and it is very difficult to detect the exact point of this deviation, even though we trace the two lines forming the deviation itself, as shown in the bottom half of Fig. BO.24.



Fig. BO.24 – CorrMap lets you precisely detect line deviations that are nearly imperceptible.

CorrMap lets you easily select that point with high accuracy using the following steps:

1.Trace the two lines forming the deviation as shown in Fig. BO.24 above.

2.Select the two lines just traced using the Select command (explained in the Tools paragraph at the beginning of this section) with the Lines snap option described above. The color of the selected lines will then turn to magenta.

3.Activate the Break line command in CorrMap toolbar (4 in Fig. BO.19). This option divides each of the two lines in their intersection point.

4.You can now select exactly that intersection point during your transformations. To do so, leave the Lines snap option active and use the appropriate transformation command to select points (Reference point, Grid point, Transforming point, etc.). Move the mouse over the intersection point until you see the little square (snap) and click on it, as shown in Fig. BO.25.


Fig. BO.25 – You can easily select guide line points using the snap.

Grid lines

The commands included in this box of CorrMap Home toolbar are explained in section Transformations | Affine | Tracing grid lines.

Grid points

Import grid points

This command imports grid-points exported by the program Geocross. Geocross is a Tecnobit's software program that automatically detects the grid-points at the intersections of grid-lines for maps provided with these features.

Suggest coords

This CorrMap option is very useful during transformations based on grid points, such as the Affine and Grid transformations, because it will automatically suggest to you the map coordinates of the grid points as you click them. Let's see how it works by recalling the Affine transformation example explained in section Transformations | Affine. Once we have inserted the first grid point and provided its coordinates (Fig. TR.4 in that section), we now want to insert the second grid point in the position shown in Fig. BO.26. So, we zoom that grid point and we click on it. As you can see in Fig. BO.27, the program suggests us the Easting of this second grid point in the coordinates dialog box.



Fig. BO.26 – Once we have inserted the first grid point ....


Fig. BO.27 – .... CorrMap suggests the Easting of the second grid point.

How can the program provide this coordinate? It simply detected that we clicked the second grid point in the same vertical position compared to that of the first grid point, i.e. the Easting is just the same. So we only need to type the Northing value of 54200, as indicated in the map. Well, let's now proceed by inserting the third grid point in the position shown in Fig. BO.28. Again, we zoom on this grid point and we click on it. As you can see in Fig. BO.29, the program now suggests both the Easting and the Northing of this third grid point.


Fig. BO.28 – And after inserting the first 2 grid points ....


Fig. BO.29 – CorrMap suggests both the Easting and the Northing of the third grid point.

How can the program provide both coordinates? For the Easting, as before, It detected that we did not move from the same vertical position. For the Northing CorrMap calculated how far we moved from the second grid point. comparing this distance to that between the first two inserted grid points. As you can see in Fig. BO.29, the coordinates proposed by CorrMap are exactly those written in the map. Please note that there's no need that the third grid point is in the same vertical (or horizontal) position compared to the first two grid points, it could be at any other position and CorrMap still calculates its coordinates. Of course at this stage CorrMap will now be able to suggest the coordinates for all the other grid points we are going to insert.

Suggest grid-points

As for Suggest coords this CorrMap option is also very useful during transformations based on relevant number of grid points, such as the Affine transformation, because If you select it, the program automatically suggests the position of all the grid points based on the first two that you inserted. Here is how it works: you insert the first two grid points as explained in section Transformations | Affine, then you activate this command and you'll see a red circle appearing in the position where you should insert the remaining grid points, as shown in Fig. BO.30. The position of these new grid points is calculated by CorrMap based on the interval between the first two grid points already inserted, making the assumption that you want to maintain the same interval between all the remaining grid points to use for the transformation. In this way you can easily locate the other grid points to insert, zoom in and click each of them, as shown in Fig. BO.31. Once you have clicked a point, the suggesting red circle disappears.


Fig. BO.30 – CorrMap suggests the position of all the grid points based on the first two that you inserted.


Fig. BO.31 – It is then very easy to locate and click all the remaining grid points using the same interval.

Renumber grid-points

This command is explained in section Transformations | Affine | Renumbering reference points.


image423 This command provides the coordinates of a point on the map in CorrMap's graphic area. You can click at any point in the map or you can select a point that you have previously inserted using a CorrMap transformation command, such as Grid point, Reference point, Transforming point, etc. In this latter case, you just need to activate the Snap option described below. Once you have clicked or select a point in the map, its coordinates appears in the bottom-left side of the status bar as shown in Fig. BO.32. Of course these coordinates can be the real map values if you had previously geo-referenced the map, otherwise they are simply the pixel values referred to the origin in the lower-left vertex of the raster.



Fig. BO.32 – CorrMap gives you the coordinates of map points.

image425 This command gives you the distance between two points in the same way as for the Point command,  you can click any two points on the map or you can select points that you have previously inserted using a CorrMap transformation command. Once you have clicked the first point, you see an elastic line starting from that point so you are visually aware of the distance you're querying. So, with this elastic line you select the second point and you'll see the distance value displayed in the bottom-left side of the status bar as shown in Fig. BO.33. As mentioned above, this distance is in real units (e.g. meters) only if the map was previously geo-referenced using one of CorrMap's transformations, otherwise the value is in pixels.



Fig. BO.33 – CorrMap lets you query the distance between two points on the map.

image427 In the same way as CAD systems, this command toggles the snap selection to points on the map. Activating this option, the Select command (described in the Clipboard paragraph at the beginning of this section), allows you to select points that you have previously inserted on the map (Reference points, Transforming points, etc.). To do this, just move the mouse cursor over the desired point and you'll see the little red snap box indicating that the program has exactly identified that point.