topic Re: Raster to vector in ArcGIS Online Questions

Raster to vector

AmitaGnana_Prakash — Tue, 19 Jan 2021 14:18:37 GMT

Hello, I have a raster population density map.

I converted the raster to points.

What kind of data can I get from these points? Does one dot represent any 'number of persons'?

Thank you in advance for your reply!

Re: Raster to vector

DavidPike — Tue, 19 Jan 2021 14:31:00 GMT

What was the population density raster indicating? For example, something like LandScan would have each cell representing the total number of persons. When a raster to point is performed, the points are attributed with that value (number of persons). By converting to points you're also losing the extent of the area which is being estimated.

Basically it entirely depends what the raster was showing.

What are you intending to do with this and what is the initial raster?

Re: Raster to vector

DanPatterson — Tue, 19 Jan 2021 14:42:49 GMT

Each point will have the value associated with that location.

I would definitely not interpret it as the number of persons at that location as David indicates.

Converting it to points? Why? What do you intend to do with it?

Re: Raster to vector

AmitaGnana_Prakash — Tue, 19 Jan 2021 15:00:52 GMT

Thank you for your reply.

I downloaded the raster population density image in tif format from an open source.

The metadata shows - "Estimated total number of people per grid-cell.m at the equator"

The purpose is to get the total number of people in the city that have easy access to a particular facility like a supermarket. Since population data is not available, and the only resource is this population density raster image, I converted it to points, created a buffer around the facilities and selected the points which fell within this facilities buffer.

Would there be another way to find the number of people having access to the facilities?

Re: Raster to vector

AmitaGnana_Prakash — Tue, 19 Jan 2021 15:02:19 GMT

Thank you for your reply.

I would like to get the total number of people having access to a particular facility.

And population density raster image is the only source available.

Re: Raster to vector

DavidPike — Tue, 19 Jan 2021 15:34:37 GMT

It might be a reasonable way to do what you're intending if the raster cells are small compared to your buffer areas, if not - then there's not great deal you could do in any case. what resolution is the raster?

Zonal statistics on the original raster would also work, its conceptually the same process but without the need to turn the raster cell centroids to points.