I downloaded some free geospatial data (Vector files and Raster images) from the divagis.org site but seems like the degree of accuracy of that data is questionable. Please advise me on whether i should generate my own vector files or continue using it.
This depends on how much meta-data came with the download, or is posted on the site. I would imagine that the folks at Diva would be glad to answer any questions you had if you contacted them regarding the data. They have a nice contact form on their site that you can fill out with your questions. Additionally, keep in mind what degree of accuracy your project actually requires.
I agree with Daniel - contact the Diva GIS people. Depends on what you were expecting of their geospatial and attribute data and how you were going to use them.
It depends on the scale of your AOI. For instance if you are looking at a very small spatial area and use a dataset made for the entire country, you will have generalizations. Also projection can cause errors because projections are based on what variable is important to you, such as is shape more important than size.
One of my tricks is to compare any data I download to 1:24000 USGS quad maps. They have a known and published accuracy - and usually have enough information to compare to almost any dataset.
I agree with Matthews and Nash. it is depend on the purpose of using the data. for example if you want the data for flood analysis, then it should need highly accurate data. if you look at data from OSM, research by Haklay et al have identified that OSM data is comparable to use at certain area to complement the Mapping provider data. and I agree with Hickey that you can used other dataset just to check whether the accuracy is acceptable for your purpose...then you can proceeedd
First, I would say that the cost of data is not always proportional to their accuracy (or quality). You have some very good datasets that are free, either produced by crowdsourcing (like OpenStreetMap) or distributed for free by governments. Second, some (but few) datasets come with metadata that will characterize the quality of the data. Finally, a good indication of the accuracy is indeed, as suggested by others, the scale of the map. Large-scale maps (= local) will tend to be created with higher accuracy standards than smaller-scale ones (= global). Maps that will appear to be inaccurate (e.g. poor shapes for roads) will just be maps that are not meant to be used at a higher scale. So try to find the data that fit your intended use.
- Badges
- Science topic
- Similar topics
- Geoscience
- Geoinformatics
- Geographic Information System