Get spatial accuracy

[xmichael]

About
Takes number of satellites, input accuracy , min. Satellite Threshold, min. Accuracy threshold (the lower the better) and returns 2 boolean values to indicate if satellites and accuracy do not exceed the threshold.

Notes

• This is only two simple greater-than comparisons. Still, people will not use it if it is not there so it is good to have it to help in the brain-storming of use-cases.
• Might eventually drop the "min. Sattelite test" (too crude) and/or integrate the "min. accuracy test" with other tests depending on use-case. Food for thought.

[gmh04]

Current algorithm in GetSpatialAccuracy.java amounts to:

if(numberSat >= minSatNum){
    resultFeatureBuilder.set("DQ_SpatialAccuracy", 1);
}
if(numberSat < minSatNum){
    resultFeatureBuilder.set("DQ_SpatialAccuracy", 0);
}

if(acc >= minAcc){
    resultFeatureBuilder.set("DQ_AbstractAccuracy", 0);
}
if(acc < minAcc){
    resultFeatureBuilder.set("DQ_AbstractAccuracy", 1);
}

Is this useful? If so, possible signature of new function(s):

boolean isAccurate(double acc, double minAcc, int numSat, int minSatNum)
boolean isAccurate(double acc, double minAcc)

[xmichael]

Looks good. It is probably not that useful in its current state but it serves as documentation of what's there. Also it is possible that Julian might use it for WPS refactoring.

In practice this will probably become a test conditionally executed by FTOpen.

[DrDids]

Just saw this (though I kind of rarely look at the github emails)
A comment: the right element is DQ_AbsoluteSpatialAccuracy and will be the reading from the Android API .GetAccuracy() or similar in IOS, which I believe is the standard measure of the half of the interval for a 68% confidence interval, i.e. corresponding to 1sd.
Nonetheless criterion of "usability" or extra confidence in the position and indirectly to that measure (this time a metaQuality) can be sued with this algorithm:
if (numberSat >=minSatnum) then DQ_Usability is 1 or a % related to a function of numberSat/minSatnum ... so less uncetainty in the position and its accuracy
else DQ_Usabiity is 0 or a % related to the ratio .... as metaquality we didn't have enough info to calculate the acuracy and indirectly more uncertainty in the position and its accuracy.

To be simple we can use only the DQ_usability as quality element but we could do both i.e. putting it as well in metaquality see the ISO19157 to do this.

Idem for the test on acc >=minAcc

Then I would set up a Cleaning QC in Pillar2 that deals with usability and or quality element values specifically. I know this is not Basecamp and this answer is too long. Sorry!