How often do I need to replace my geodata?
Unfortunately, there is no single answer to this question.
Part of the answer requires an understanding of your environment and how much change it is undergoing.
For instance, city centers in many western European areas do not demonstrably change year over year.
However, in countries such as India, the UAE and elsewhere a 12‑month period can translate into a dramatically changed landscape.
ComputaMaps recommends that most geodata sets are investigated every two years.
This could mean a simple call to your account manager enquiring about the latest on‑the‑shelf project.
It could also be an assessment through our proprietary Change Detection System.
What resolution of data should I use for planning my LTE overlay?
We typically recomend 5m resolution or higher for planning in an urban environment.
If the LTE network is being deployed outside of urban centers (e.g., using 700 MHz spectrum) then standard 2D 20m data can be employed.
Can I update a single layer of data for my project (i.e., clutter) without updating the others?
It is not recommended.
At a minimum, you should continue to use the same vendor if updating a single layer.
All layers of a geodata project – DTM, building polygon, clutter, street vectors – should be derived from the same imagery.
If only a single layer is updated, the likelihood of it being correctly georeferenced and usable with the other layers is quite small.
What is the difference between satellite and aerial imagery?
There was a time when aerial imagery was preferred for 3D model creation because it was easier to get at high resolution.
Today, the improved capture capabilities and competition amongst satellite providers means that recent imagery is available at sub-meter resolution for virtually anywhere in the world.
At ComputaMaps, our default source for all of our data is satellite.
We augment this supply by aerial data where required, such as in a tropical area where cloud cover means little useful satellite imagery is available.
What is the highest resolution of geodata available?
ComputaMaps can deliver geodata at less than one meter of resolution.
How can one of your competitors provide a much larger data set for a lower cost?
This is also a difficult question to answer.
While we have experienced situations where competitors are offering data below our costs to deliver it, this is not common.
We have witnessed many new entrants that tried to establish themselves as the low-cost supplier come and go over the years.
Our prices reflect the costs of our inputs and our delivery system, along with a fair profit.
However, if a price seems too good to be true, it just might be.
Geodata can be output at virtually any resolution, but unless the source imagery and related mapping data is at equal or higher resolution their accuracy can be quite dubious.
A DTM provided at 5m resolution derived from 20m imagery will only be as accurate as the 20m source data it was based upon.
Why don’t you have a particular city in your catalogue?
We produce data sets to satisfy explicit customer requests or on a speculative basis to meet anticipated market demand.
We can’t always be right, but our unmatched capabilities in developing 3D data means that if we don’t have your city on the shelf, we’ll be able to deliver a new data set quicker than our competitors.
Why doesn’t your data correspond with what I can see in Google Earth™?
Another tough question!
Google Earth™ (or other free online mapping applications) is used by virtually every RF engineer. The imagery it utilizes is provided by different vendors around the globe.
This data may be newer – or older – than the imagery used by ComputaMaps to derive our geodata.
That is one possible reason for the discrepancy.
Another reason is the potential misclassification (i.e., human error) of a clutter area as part of our development process.
ComputaMaps strives to achieve a high level of accuracy on this effort, and our R&D is focusing on ways to improve this through process automation.
What is a minimum mapping unit?
The mininum mapping unit is the smallest area for which an individual clutter class will be represented in the clutter layer.
For example if the mininum mapping unit is 20m x 20m (400 square meters) a stand of trees measuring 100 square meters in area will not be represented in the clutter layer.
Keep the questions coming! Send your questions to us and we’ll integrate them into future articles and newsletters.