Questions tagged [data-quality]

for questions related to implementing best practices to ensure good quality in gespatial datasets; including quality assurance (QA) and quality control (QC)

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1answer
51 views

Google Earth Engine Mask application

I'm using GEE in order to extract evapotranspiration (ET) data from MODIS (MOD16A2v6). I want to extract only ET band in order to make some further process. To do so, I apply some filters (like ...
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0answers
31 views

What is Kappa coefficient in HSI classification? [closed]

What is the Kappa coefficient and how it is calculated in the HSI classification process?
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0answers
19 views

Download QA band of Landsat 1-8

In one of my work, I just need the QA band of Landsat, but USGS Earth Explorer does not provide band by band data download opportunity. As I am interested to get all the available Landsat QA data from ...
2
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1answer
80 views

NDVI index based on QA bands for MCD43A4 , in GEE

I want to calculate the NDVI index based on the MODIS/006/MCD43A4 collection and based on quality bands, but as a new GEE user I have no idea If I am on the rght way to do this. So far I have the ...
0
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1answer
88 views

Select observations based on Quality Bands , Google Earth Engine

From the following NDVI collection, I want to keep only the observations with Good Quality (equal to zero). I try to do this with the SummaryQA but I get "Pattern 'SummaryQA' did not match any bands"...
2
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1answer
72 views

What are the other bits in Sentinel's QA60 band?

According to this page on Google Earth Engine documentation bit 10 is 1 for dense clouds, and bit 11 is 1 for cirrus. The documentation doesn't say anything about all the other 14 bits that can be set,...
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1answer
35 views

Does the MODIStsp package computes the QA's and eventually corrects the bad quality pixels?

I am using R's MODIStsp package for downloading MOD11A2 time series products. While executing the command it was written that QA's were computed. Several files were created, LST_Day_1km, QC_Day, ...
3
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0answers
46 views

Hansen loss and lossyear bands do not always match in Earth Engine

I'm looking at the Hansen forest loss v1.5 data in Earth Engine. According to the Hansen documentation, In addition, to reduce confusion, beginning with version 1.4 we are no longer releasing loss ...
5
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1answer
232 views

LiDAR returns over water bodies?

I have obtained LiDAR data from my environmental agency in order to obtain the relative heights of each watercourse station. A far as I know, LiDAR signals do not get returned over water bodies. ...
5
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3answers
162 views

How to check accuracy of Roads

We've been doing QA work on a roads dataset and I realized that many of the roads don't overlay correctly with their counterparts in Google Maps or OSM. Currently we compare our roads with the ...
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0answers
54 views

Geospatial quality standards

I am reviewing the geodata quality standards within my organization. During my review I keep coming across the ISO 19100 series. I am wondering if anyone has used these standards and if they have any ...
1
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1answer
330 views

How to extract MODIS QA informaton

I want to use the LDOPE tool unpack_sds_bits to extract the bit information from the State QA layer of the MYD09GA Aqua Surface Reflectance product. However, I have never run a command line before ...
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1answer
74 views

Discrepancy between shape area and data from municipality [closed]

I am attempting to map several parcels just to show very basic dimensions (frontage, etc.) and parcel area. I have the parcel area from the municipal assessor's office in acres. And I have a parcel ...
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0answers
196 views

MODIS Quality Control in QGIS

I have to process 46 MODIS MOD15A2H images (leaf area index) in QGIS 2.12 Lyon. I have to clean the images from bad pixels using MODIS Quality Control. Is there any method to automate the process for ...
3
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1answer
577 views

MOD09A1 QC layer

Does anyone know how to handle MOD09A1 Quality flags (QC) in in R? I was trying to use raster package but unable to unlock the QC band.
3
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1answer
47 views

How can I select ways that have missing access parameters “[key]=Not Specified”?

Follow up to How can I programmatically identify missing sidewalks in OpenStreetMap data?. I've noticed that a number of streets and roads in a region I'm interested in are missing pedestrian access ...
2
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2answers
242 views

How can I programmatically identify missing sidewalks in OpenStreetMap data?

I have a web map that is using the pedestrian routing from Mapbox's directions API. However, users have seen very long circuitous paths in certain locations because it appears that sidewalks (and/or ...
4
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2answers
413 views

How to correctly parse MODIS QA layers?

I'd like to correctly parse the MOD13Q1 VI Quality layer (see Table 2 in "layers" here). For this, I'm trying to follow Example 1 from this tutorial (page 10). I'll illustrate my problem with a pixel ...
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0answers
74 views

Changes in MOD09A1 quality mask as processed with GDAL

I'm analyzing MOD09A1 spectral data using GDAL/Python. The quality mask is a uint32 dataset and want to pull out the value of the first bit to mask the spectral data (1 == poor data; 0 == good data). ...
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2answers
1k views

Raster images losing quality when clipped?

I'm using the ArcGIS data management clip tool for raster, a jpg file. It is being clipped with a polygon. After the clip is successful, the clipped image is appearing in lower quality and the colors ...
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2answers
100 views

Implementing transactions with Collector for ArcGIS?

Currently I am looking into using ArcGIS Collector for field use. I would like for there to be a QA process done before final submission. Is there a way to implement an approval process for the ...
0
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2answers
62 views

Ensuring data quality from organizations

You are working for an organization that receives data from other organizations in different data formats (geospatial files, spreadsheets, text files, etc.) Is there specific things you would ask ...
6
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1answer
2k views

How can I parse modis MOD13Q1 quality layers in R?

I'd like to parse MOD13Q1 VI quality layers in R. My original code must have been incorrect, because it gave lots of "deep ocean" flags in the middle of Brazil. After the changes suggested by Mikkel,...
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0answers
58 views

Collecting shapefiles from different users - any rules for quality data/quality control?

Apologies in advance for this very basic question! My company collects market information from forestry projects in an annual survey. This year, we are trying to add a spatial element to our analysis....
2
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2answers
345 views

Why OSM data has different attribute values from the same element and same time frame?

Here is my question: Does anyone know why OSM has different attribute values from the same element and same frame time? The example explains itself, when I try the Shapefile from different mirrors ...
2
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2answers
185 views

What are the ways we can control the quality of a DTM?

I imagine that for DTM obtained from Stereoscopic procedures or interpolation from a set of topographic points a comparaison with the original data can help, but what for DTM obtained from Remote ...
9
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1answer
257 views

What PostGIS [topology] provided tools may be used for data quality assurance?

I'm learning about techniques to ensure GIS data quality. Googling around, I've found a few papers about theory and best practices (here and here), and a couple of short presentations about the topic ...
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1answer
354 views

Utility GIS - Type of data cleanup needed & Effort

I am trying to get into Utility GIS and I have been asked by my boss to size up the effort of what it takes to clean up Pipeline, Utility asset GIS data and figure out if there is a way think of a ...
5
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2answers
425 views

How to check if Waste-Water Manhole connect to lines with the right flow direction?

I have a waste-water geometric network with flow direction throw digitize direction. I want to check if each manhole have a line flowing in and a line flowing out. Is there an attribute of line vertex ...
2
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1answer
458 views

Using line of sight or something similar to identify where lines go through hills

When QCing power infrastructure I am having to zoom into every gap and check to make sure the line makes sense (not going through the mountain). I typically check for odd spacing between the pylons ...
2
votes
1answer
791 views

Validating Values in Multiple Fields in an Attribute Table

I've been playing around with 'Maintaining Attribute Integrity' functions found here: http://resources.arcgis.com/en/help/...000000n000000/ I see how I can set domains and subtypes to control the ...
1
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1answer
227 views

Running a QC check for gaps between vertices on a polyline

I'm checking polylines to make sure power pylons were correctly extracted from imagery. Is there a way to find all of the gaps or missed pylons in the database? Currently, I'm manually making a ...
4
votes
1answer
1k views

Automated quality control and assurance - geodata?

I've recently started looking at the issue of automated quality control and assurance of geographic data. What software exists that can be used for accomplishing this? Esri has got their product '...
11
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2answers
9k views

Finding differences between shapefiles using ArcGIS for Desktop?

Every month I have to QA/QC some streets data for an entire county (over 47,000 records). The first step is to compare the two files. Currently, I'm using a tool that was created in house via VBA ...
3
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0answers
275 views

Is there a tool for automated quality assurance for vector data captured on raster data? [closed]

I wonder whether is any tool(or script) in ArcGIS or QGIS which allows to make an automated quality assurance for vector data captured on raster data? vector data on binary raster:
10
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3answers
2k views

How do I compare two maps to determine which is better?

I'm trying to do an objective comparison of two different maps for the same region. At the moment, I'm struggling with defining criteria that will allow me to do a dispassionate evaluation. Does ...
1
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2answers
237 views

How to query points that fall outside their designated regions?

I have a shapefile with 250 points. Each point has a region attribute. In another shapefile I have all the possible regions with their names (it is polyline geometry). Unfortunately the coordinates ...
3
votes
2answers
2k views

Is there website with list of common QA/QC errors?

As I am working on reviewing my soils spatial data, and I am doing my QA/QC I placed a point layer to check for errors. I add the field column to mark the error and state the error. I recently ...
5
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3answers
336 views

Methods for lat/lon quality control? [closed]

I have a database with fields including latitude, longitude, city, state, and country. When mapped, it is clear that a number of the sites are in the wrong location - most commonly because of a sign ...