OpenStreetMap
Gregory Peony's Comments
| Changeset | When | Comment |
|---|---|---|
| 157281198 | All but perhaps one or two building footprints outline buildings. All buildings have been squared. The imagery allows for greater accuracy in the orientation of a few of the buildings in this changeset. For instance WAY: 1319465402, WAY: 1319465412 & WAY: 1319465413. There is a sweet spot called the 'native resolution' where 1 pixel of imagery is assigned to 1 pixel on your screen. It allows you to make the most accurate observations regarding orientation and shape. In JOSM you can right click with imagery loaded and choose the option 'zoom to native resolution' to view at this zoom level. Take a note of what you see, (mental or otherwise) then zoom in to accurately draw buildings on the map. Repeat as necessary. Thank you for your contribution!
|
|
| 157543028 | Well done! All of the building footprints you've added outline builldings in the imagery and have appropriately squared building footprints. The orientation and size of some buildings could be more accurate. When it comes to determining orientation and shape there is a zoom level sweet spot where one pixel of the imagery correcponds with one pixel on your screen (in this case it's zoom level 17). Some of the building footprints you've added appear too large. Generally: Building Footprint Size<= Roof Size. So without information to the contrary the footprint should be equal to or smaller than the roof. When squaring the area you've drawn in ID editor the shape will most likely change somewhat; you can draw footprints ~95% of the roof size to give yourself a margin. This is especially important to keep in mind when working in densely populated areas where buildings can be very close to one another to avoid footprint overlaps. Thank you for your contribution!
|
|
| 157826283 | Well done! Both of these building footprints are valid and for the most part accurate and have been appropriately squared. The orientation of the building to the south is not quite accurate. Though it does appear as though the building is oriented East to West when you zoom in, this is an illusion caused by the low resolution. When you zoom in one pixel from the original imagery may be represented by many on your screen. If you're zoomed out really far then an entire building may be represented by just one pixel. Features will trend toward looking like they are either North/South or East/West when at very high or very low zoom. There's a sweet spot that'll give you the greatest resolution, this helps with determining building shape and orientation. Then zoom in to accurately map while keeping what you've seen in mind. Thank you for your contribution!
|
|
| 157914023 | Well done! Both of these building footprints are valid the one on the right is quite accurate, but the one on the left has not been squared when it should and is slightly too large. I modified these footprints and uploaded my changes for you to see. Click on a feature and open it in ID editor to see what I've done. Thank you for your contribution!
|
|
| 157964767 | Well done! The building footprint you've added here is valid and mostly accurate, it's just a little bit too large. Building footprints are generally either the same size as the roof, or smaller. If squaring the footprint causes it to become too large, then you can map ~95% the size of the roof before squaring. I shrank the footprint and uploade so you have an example. Click on the feature in this changeset and open it in ID editor to see it then toggle OSM data via the map data panel. Thank you for your contribution!
|
|
| 158185394 | Well done! All of the building footprints you've added in this changeset are valid (visible in the imagery you used to trace them), and most are accurate and appropriately squared. The accuracy of some however, could be improved. All of these footprints in this case should have been squared. Imagery is not perfect and it may sometimes distort the true shape of a building, you should interpret the imagery and add what you believe to be the case on the ground. For example the feature I flagged should be square, it seems that trees are obscuring part of the building, but in reality it is most likely square. I recommend zooming out to determine shape and orientation, then zooming in to accurately map. It is also possible to edit a feature once added e.g. move & rotate Check the shortcuts in the help panel of the ID editor. Thank you for your contribution!
|
|
| 158240752 | I think that this footprint actually outlines two buildings because the orientation of the footprint you've added does not match the imagery, the color is different on either side and there is a dark line (shadow) seperating the different colours. The shadows are cast Sout West in ESRI imagery in this area. I mapped the two buildings I see in place of this one, and uploaded them so that you can see my interpretation of the imagery (click on this feature and open it in ID editor, then toggle the OSM data via the map data panel). I hope this helps. Thank you for your contribution!
|
|
| 158240891 | All of the footprints you've added are valid. Their shape however, could be more accurate. Please place nodes in the corners of buildings accurately (enough), tag the area as a building, then press 'q' to square the footprint. The resolution of ESRI in this area is not the greatest but, these buildings appear to have 'square' footprints in reality. I recommend that you use Mapbox imagery in this area to help determine the shapes of buildings where possible and to zoom out to better see the shape of features before zooming in to accurately draw them. Thank you for your contribution!
|
|
| 158316372 | Just for fun I uploaded a guess of these building footprints based on ESRI imagery alone, they may not be as accurate as if I had used Mapbox, but I wanted to give you an example of what to do in these situations. You can find the changesets via the top right of the task menu in the tasking manager (under task data), or near the bottom of the project main page (changesets in OSMCha).
|
|
| 158316372 | Most of the building footprints here are inaccurate. Again it's a question of imagery interpretation. Features in imagery; like trees, walls or buildings can obscure others. In situations like these you should try to work out what is the shape of a building (in this case) likely to be. Sometimes different imagery sources can help with this, other times you'll have to give it your best guess. In this case all of the building footprints should have been squared, given the low resolution imagery you were working with and the architecture of the surrounding buildings. It was more likely that the imagery was distorted or that the building was partially obscured by trees/vegetation than it is for it to have this unique footprint. Buildings tend to take take on this shape near highway intersections of 'odd' angles. I hope this helps.
|
|
| 158315601 | Overall this is a high quality contribution. Well done! All buildings digitized in this changeset are in fact buildings, and the majority of them have accurate footprints, and are squared appropriately. There are some inaccurately shaped outliers however, which I believe is due to you missinterpreting the imagery. I encourage you use Mapbox imagery as a suplimental source, because it has a greater resolution in this area. That should help you better determine the shapes of buildings. If the available imagery is if poor quality you should interpret it and add buildings with likely shapes. Ask yourself: What shape is that building likely to be? Is it actually that shape, or does it just look that way on the imagery? Thank you for your contribution!
|
|
| 158254555 | Buildings and roads should rarely overlap or share nodes. That may be the case at a petrol station where the road passes under a 'roof' but generally they should not becasuse it could affect some routing software. When in close proximity to other digitized features hold Alt to prevent your cursor from snapping to them. I have modified these features to provide an example. Some of the building 'outlines' do not match up with the roofs in the imagery. This is because we are aiming to map the building footprint (where the walls meet the ground) so that the map is accurate in 2D. Check the OSM carto imagery layer to get an idea of what your mappings look like to others. Thank you for your contribution. I hope my feedback helps you to improve the quality of your mapping.
|
|
| 158255095 | Well done! You identified buildings in the imagery and I don't think that you outlined anything other than a buiilding. The buildings' footprints however, are not accurate. The low resolution imagery does not help, but you need to interpret the imagery and give buildings realistic shapes rather than tracing distorted imagery or artefacts. I recommend that you find a task area where Mapbox imagery shows on the whole the same buildings, because it has a greater resolution in this area. This will allow you to compare what the same buildings look like with different levels of resolution. When you must work with low resolution imagery zoom out first to ascertain the shape and orientation of buildings, then zoom in to digitize them accurately (you can repeat this of course if you forget the shape for example). Quality > Quantity. Thank you for your contribution.
|
|
| 158206496 | Please square your footprints if a building's walls form right angles. The feature I flagged consists of a surplus node. Overall this is a good contribution; all features are valid. Zooming out can help you see the shape and orientation of features, then zoom in to draw the feature accurately. If you want to you can use mapbox imagery in this area (either to trace or as a supporting reference) by offseting it to allign with the features you've already mapped, since the resolution is greater. I encourage you to attend this online event if you'd like to interact with other mappers. https://osmcal.org/event/2725/ or search for it through OSMCal
|
|
| 158290227 | I made some modifications to the buildings in this changeset, hopefully for you to use as a reference. Thank you for your contribution.
|
|
| 158290227 | Well done! You have correctly identified all of the buildings digitized in this changeset, and the vast majority of footprints you've drawn here are quite accurate, although they should be squared (q on keyboard after tagging). You've done a good job placing the nodes with your cursor, but it's very unlikely that you'll get it spot on, and the q keq will make the corners right angles. The feature I flagged has too many nodes, and I think it's actually two buildings given that the shadow is cast West in the imagery you used to trace it and there is a dark line between the two light parts.
|
|
| 157085950 | Although I have verified this changeset as bad, there is a lot that I like about it too. For instance you've squared the majority of rectilinear buildings that you've added in this changeset. In places you followed good practice and modified features rather than deleting the old ones and adding new ones in their stead, (and in some cases improved existing mapping). I also like that you decided (seemingly part way through) to use an alternate imagery source in this area, because it had a greater resolution. If you want to improve the first points I'll give you is to draw building footprints slightly smaller, ~95% the size the roof you see in the imagery. Hold the Alt key when adding nodes close to existing features to prevent your cursor from snapping to them.
|
|
| 157085950 | Although I have verified this changeset as bad, there is a lot that I like about it too. For instance you've squared the majority of rectilinear buildings that you've added in this changeset. In places you followed good practice and modified features rather than deleting the old ones and adding new ones in their stead, (and in some cases improved existing mapping). I also like that you decided (seemingly part way through) to use an alternate imagery source in this area, because it had a greater resolution. If you want to improve the first points I'll give you is to draw building footprints slightly smaller, ~95% the size the roof you see in the imagery. Hold the Alt key when adding nodes close to existing features to prevent your cursor from snapping to them.
|
|
| 156886825 | Thank you for your contribution. You correctly identified the vast majority if not all of the buildings that you digitized in this changeset. Their shape however is not very accurate and a number of features overlap and share nodes. Refer to the editing shortcuts in the help section of the ID editor for 'squaring' and 'avoiding cursor snapping'.
|
|
| 156886751 | Well done, all of the features that you added are in fact buildings. Their shape however, is generally not accurate; all of these building footprints are actually recti-linear, and so should have square corners (press q on the keyboard after accurately tracing). To be fair the imagery you used to digitize the footprints does not have the greatest resolution. If you choose to contine contributing I recommend that you find a project with clearer imagery to gain familiarity with building shapes.
|