Clean Unnecessary Points - New Feature

 This article was written to describe a new feature that will be included in the release of iMapIt`s version 4, to illustrate it and bring understanding of its use.

“Clean” is a quick way to purge unnecessary parts of a mapping measurement. When we collected a large number of points and we would not necessarily need all those points, we can clean them automatically.

Observe, for example, the measurement shown in the image below, of an approximately rectangular area, where we had collected a coordinate for each of the small blue dots highlighted.

Note that there are several points that apparently are part of the same line shape. In the example above there are only a few points. But imagine measurements with hundreds or even thousands of points and where many of them could be removed without prejudice to the contour of the area. We would save a lot of space not only on our equipment, iPhones and iPads, but also transfer time and further processing time if we were to take these measurements into other software.

What if we could have a quick way to remove these “unnecessary points”, obtaining a measurement with the same contour and with fewer points, as shown in the figure below?

This is the goal of this new function called “Clearing Unnecessary Points”. In version 4 of iMapIt it will appear among the many other new functions available for handling a feature shape.

And how does this new function work?

Setup:

In this new version, a new option for automatically collecting coordinates was introduced, which collects a new point with each change of direction in your displacement. This type of automatic collection due to changes in the movement direction introduced a new parameter: an angle of inclination. This angle defines the limit that iMapIt can accept between the previous line segment collected and the new one that is about to be created while you are moving. A new coordinate will be collected when this angle is reached.

This angle is defined in the settings screen and can be changed at any time as needed. The image below presents this new functionality in the settings screen.

The “Clean” function uses this same angle to do its job. Above we see the standard angle that is initially defined: 1^o30’ 0” (one degree and thirty minutes) of inclination.

Its logic:

Note that each feature is made up of a sequence of points. When the feature is of the “Point” type, the collected points are presented individually. When the feature is of the “Line” type, the points are concatenated in the sequence in which they were collected, so that they form a line. And finally when the feature is of the “Polygon” type, just like the “Line” type, the points are concatenated in the sequence in which they were collected, so that they form a line, but the last point is automatically joined to the first so as its shape becomes a closed polygon, which defines an area.

Also note that for the “Line” and “Polygon” feature types, each line that forms its outline is formed by a sequence of straight lines segments. Each line formed by two consecutive points. These line segments form angles to each other, as shown in the figure below.

The “Clean” function eliminates points that are between two lines that form an angle smaller than 1^o 30’, or any other angle that is defined. Thus, the feature will have fewer points to represent a shape very similar to the previous one.

Before

After

This function does not change the original feature. It creates a new feature where the “unnecessary points” have been eliminated. If you are satisfied with the result and no longer need the original feature, you can simply delete it.

iMapIt version 4 – New Features

We have a new version of the iMapIt app in the oven and almost ready to be published on the AppStore. It is expected to be published in mid-December. It is version 4. For those who already have a previous version, this will be just an update.

 

However, this version brings a significant number of improvements and the purpose of this article is to present them succinctly.

 

 

Improved map display while measurements are being collected

In previous versions the map always had a fixed orientation, oriented to the north, unless you explicitly place two fingers on it and rotate it.

In the new version there is a new feature that rotates the map according to the orientation of your device. If your iPhone / iPad is pointing south, the map is oriented to the south. If the device is pointing to the east, the map is oriented to the east. It will always follow your movement.

When this feature is turned on, the possibility of viewing the map in 3D is also available, so that you feel inside the place where you are traveling.

 

 

Automatic coordinate collection feature added

In previous versions, when taking a measurement, you always had to touch the “MapIt” button to collect the coordinate at the place where you were. This way of collecting coordinates continues to exist and is now called “Manual Collection”.

From this new version, three new ways of collecting coordinates fully automatically were added, that is, you do not need to touch the “MapIt” button to collect the coordinates.

·      Collection by Time – A new coordinate is collected at each time interval, defined in seconds;

·      Collection by Distance – A new coordinate is collected at each interval covered by a certain defined distance, according to the standard unit defined in the App, which can be meters, inches, yards, etc. If the collection distance is set to 5 meters, a new coordinate will be collected every 5 meters from your displacement;

·      Collection by Direction – A new coordinate is collected each time you change the horizontal angle of your displacement, that is, each time you change direction. This angle is defined in degrees, minutes and seconds;

 

Automatic collection assumes that you will be on the move. Not necessarily at constant speed, but always in motion. This information is important because the varying accuracy of the iPhone / iPad GPS can cause unwanted coordinates to be collected, even when you are standing still.

To assist in this possible pause in your movement, a new button was included, just below the “MapIt” button that will allow the collection to be paused for later resumption. This button will also show you how your displacement is changing so that you have an approximate notion of the time of the next coordinate collection in elapsed time, distance traveled or angulation of your displacement in relation to your last direction.

Automatic collection continues to work even if your device is off, locked.

 

The wizard functionality, which helps you choose the options to perform your measurements, has been expanded to include automatic collections.

 

 

A set of functions to edit features were added

The screen showing the details of a feature / measurement has been completely rebuild.

Now your feature map can be expanded for a better view of your details and for easier manipulation. When the map is expanded small points are presented where each coordinate was collected, for the line and polygon feature types.

 

The information presented in the previous version remains:

·      The type of feature design (category), that is, the type of the pin, the color of the line and the filling of the polygon, which can be changed;

·      Creation date;

·      Its dimension - length for lines and area for polygons;

·      Its perimeter - for polygons;

·      Display the dimension on all other units supported by iMapIt;

·      Display of the list of coordinates;

·      It is still possible to edit the name of the measurement and add a descriptive / explanatory text about it;

·      Turn on or off the display of the length of each line segment, for lines and polygons;

 

Feature statistical information has been added:

·      Number of coordinates collected;

·      Its minimum, average and maximum horizontal and vertical accuracy;

·      The altitude variation, also minimum, average and maximum;

·      The range of latitude and longitude covered, minimum and maximum;

 

New functions have been added to will allow modifying, or editing, features. Remember that coordinates are only added through collection at their physical location, by definition. The functions described below allow all types of modifications to be made to a feature.

·      Clear Unnecessary Points - This function eliminates points that form the same line and that can be removed from the feature without affecting its shape. There will be a separate article to describe this function;

·      Duplicate Feature;

·      Join Features - Join two or more features to create a new one;

·      Split the Feature in Two;

·      Delete selected coordinates;

·      Move Feature to Another Project;

 

All of the above functions create a new feature with the changes implemented. They never directly alter the original feature to prevent you from unduly losing any information from your measurements.

The functions for Clearing Unnecessary Points and for Duplicating Features will run in the background. For features with a reduced number of coordinates, these functions will execute very quickly, and will practically have finished when the message informing the name of the new feature is presented. However, with the automatic coordinate collections new feature, the tendency is for the features to grow a lot in the number of coordinates collected. For this reason, these functions can continue to work even after the name of the new feature has been informed.

 

The new function that deserves a special mention for it is the one that brings the possibility of changing the type of the feature. In other words, if you have collected isolated points, but instead you wanted a line or a polygon, just enter the feature screen and change its type. Its map representation it’s changed automatically to become the representation of the new feature type. You will no longer need to go to the field to take a new measurement.

 

In this way we hope to make the experience of using iMapIt much more useful.

We hope you enjoy.