Accidental comment on my own changeset. OSMCha failed to load the target changeset.

Hi, the buildings you added here are generally valid but oversized. This led to issues where some footprints overlapped other unmapped buildings visible in the imagery. Unless you're sure that a building shares a wall with another it's best to map them seperately.

When mapping buildings, please trace the shape accurately. Accurate building footpritns aid population estimates and prevent issues like data overlaps. Zoom in so that you can see the outline of the building and mark the corners carefully. Exclude shadows and yards when tracing the footprint. Keep in mind that you are looking at the [roofs of buildings](roof:shape=*#Roof_shape), but mapping their footprints. Depending on how the scene is lit, pitched roofs may have light and dark sections that belong to one building. Generally pitched roofs overhang the walls of a building, so a footprint slightly smaller than the roof is accurate. You can scale selected features in ID with shift+(-/+), or JOSM with ctrl.+alt+Lclick & drag. Take care to make contributions that others can build upon.

Please do not connect the corners of buildings to other buildings or features such as highways or residential areas. In the iD Editor, hold down the `Alt` key to prevent your cursor from snapping to existing data and accidentally creating shared(grey) nodes. This [video about connected nodes](https://youtu.be/ltn1VOiq5_0) has more information and a guide.

See how I mapped the footpritns here in https://osmcha.org/changesets/171900733

Hi, you identified buildings in imagery but most footpritns you map are oversized.

When mapping buildings, please trace the shape accurately. Accurate building footpritns aid population estimates and prevent issues like data overlaps. Zoom in so that you can see the outline of the building and mark the corners carefully. Exclude shadows and yards when tracing the footprint. Keep in mind that you are looking at the [roofs of buildings](roof:shape=*#Roof_shape), but mapping their footprints. Depending on how the scene is lit, pitched roofs may have light and dark sections that belong to one building. Generally pitched roofs overhang the walls of a building, so a footprint slightly smaller than the roof is accurate. You can scale selected features in ID with shift+(-/+), or JOSM with ctrl.+alt+Lclick & drag. Take care to make contributions that others can build upon.

I hope this helps.

Hi, There's reason to believe that all footprints you've mapped here represent buildings, however they are generally oversized; please map the footprints slightly smaller than the pitched roofs you see in imagery. Thank you for your contribution. If you want to experience the OSM community or to get timely feedback from other mappers; I recommend that you attend a mapathon. You can find events here https://osmcal.org/
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#REVIEWED_GOOD #OSMCHA
Published using OSMCha: https://osmcha.org/changesets/171899921

Hi, all but one footprint you mapped represent a building; I think the round building represents a tree.

Generally the footpritns here are accurate and it looks like you took care when mapping them, please try to exclude the shadow a building casts from its footprint size. Mapping the footprint slightly smaller than pitched roofs you see in imagery can help with this, and accounts for the likely overhang of the roof.

On a few occasions it looks like you mapped only one half of a pitched roof i.e. only the dark or light side. Consider the roof shape, how the scene is lit and the shadow a building casts (e.g. its length) to aid your interpretation. roof:shape=*#Roof_shape

I flagged the footpritns for reference in OSMCha.

Thank you for your contribution. If you want to experience the OSM community or to get timely feedback from other mappers; I recommend that you attend a mapathon. You can find events here https://osmcal.org/

Why did you delete these footprints? I mapped these footprints to show you how they would look when acurately mapped. Features should not be deleted unless you have reason to believe that they do not represent things that currently exist. You should modify features you can identify if you think they are not accurate as this preserves their history. Resolved by Changeset: 171898908
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#REVIEWED_BAD #OSMCHA
Published using OSMCha: https://osmcha.org/changesets/171898656

Hi, when mapping square features please right click and select square, or press q after tagging to square the corners of features. I resolved this in Changeset: 171898709

Please keep this feedback in mind when contributing in future. Thank you for your contribution. If you want to experience the OSM community or to get timely feedback from other mappers; I recommend that you attend a mapathon. You can find events here https://osmcal.org/
---
#REVIEWED_GOOD #OSMCHA
Published using OSMCha: https://osmcha.org/changesets/171898499

Hello, you have generally identified buildings in the imagery and mapped them quite accurately. They'd be even more accurate if you map the footprint slightly smaller than the roof you see. You created some invalid shared nodes between buildings and residential areas: hold alt to prevent your cursor from snapping to existing data. If you want to map a round feature, then right click it and circularise it, or use the short cut o.

The following are more comprehensive comments regarding the previous points;

Please do not connect the corners of buildings to other buildings or features such as highways or residential areas. In the iD Editor, hold down the `Alt` key to prevent your cursor from snapping to existing data and accidentally creating shared(grey) nodes. This [video about connected nodes](https://youtu.be/ltn1VOiq5_0) has more information and a guide.

After tracing and tagging features which are likely square or round, please remember to square their corners (q), or circularise them (o), because it is almost impossible and time consuming to draw shapes so percisely by hand. Buildings with metal or pitched roofs tend to have square corners; round buildings are identifiable by the distinctive cresent shaped shadow they cast. Unless the building is clearly a different shape then it's best to assume that it should be rounded or its corners should be squared. In the iD Editor, you can right click for access to editing functions. Since roofs tend to overhang walls trace the initial shape slightly smaller to allow a buffer for any change in size that may occur. In JOSM use the [buildingstools plugin](osm.wiki/JOSM/Plugins/BuildingsTools). In ID you must draw the shape accurately enough else shapes will not completely square. This [video about squaring features in ID](https://youtu.be/Xs5wX592E1o) has more information and a demo.

Thank you for your contribution. If you want to experience the OSM community or to get timely feedback from other mappers; I recommend that you attend a mapathon. You can find events here https://osmcal.org/

Welcome to OSM! The footprint you added here represents a building in the imagery, well spotted! I think this building is actually square becasue the shadow it casts is straight. See how I mapped it in https://osmcha.org/changesets/171898153

If you want to map a round feature press o, (or right click and select the relevant function) after tagging it to circularise it.
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#REVIEWED_BAD #OSMCHA
Published using OSMCha: https://osmcha.org/changesets/171897448

Welcome to OSM! The footprint you added here represents a building in the imagery, well spotted! It is however oversized and should be squared. See how I mapped it in https://osmcha.org/changesets/171898110

When mapping buildings, please trace the shape accurately. Accurate building footpritns aid population estimates and prevent issues like data overlaps. Zoom in so that you can see the outline of the building and mark the corners carefully. Exclude shadows and yards when tracing the footprint. Keep in mind that you are looking at the [roofs of buildings](roof:shape=*#Roof_shape), but mapping their footprints. Depending on how the scene is lit, pitched roofs may have light and dark sections that belong to one building. Generally pitched roofs overhang the walls of a building, so a footprint slightly smaller than the roof is accurate. You can scale selected features in ID with shift+(-/+), or JOSM with ctrl.+alt+Lclick & drag. Take care to make contributions that others can build upon.

After tracing and tagging features which are likely square or round, please remember to square their corners (q), or circularise them (o), because it is almost impossible and time consuming to draw shapes so percisely by hand. Buildings with metal or pitched roofs tend to have square corners; round buildings are identifiable by the distinctive cresent shaped shadow they cast. Unless the building is clearly a different shape then it's best to assume that it should be rounded or its corners should be squared. In the iD Editor, you can right click for access to editing functions. Since roofs tend to overhang walls trace the initial shape slightly smaller to allow a buffer for any change in size that may occur. In JOSM use the [buildingstools plugin](osm.wiki/JOSM/Plugins/BuildingsTools). In ID you must draw the shape accurately enough else shapes will not completely square. This [video about squaring features in ID](https://youtu.be/Xs5wX592E1o) has more information and a demo.

Please keep this feedback in mind when contributing in future. Thank you for your contribution. If you want to experience the OSM community or to get timely feedback from other mappers; I recommend that you attend a mapathon. You can find events here https://osmcal.org/

Welcome to OSM! All footprints you added here represent buildings in the imagery but they should be squared and sometimes you only used one half of the roof to map them. Condider the roof shape and how the scene is lit. See how I mapped the northern group in https://osmcha.org/changesets/171898065

When mapping buildings, please trace the shape accurately. Accurate building footpritns aid population estimates and prevent issues like data overlaps. Zoom in so that you can see the outline of the building and mark the corners carefully. Exclude shadows and yards when tracing the footprint. Keep in mind that you are looking at the [roofs of buildings](roof:shape=*#Roof_shape), but mapping their footprints. Depending on how the scene is lit, pitched roofs may have light and dark sections that belong to one building. Generally pitched roofs overhang the walls of a building, so a footprint slightly smaller than the roof is accurate. You can scale selected features in ID with shift+(-/+), or JOSM with ctrl.+alt+Lclick & drag. Take care to make contributions that others can build upon.

After tracing and tagging features which are likely square or round, please remember to square their corners (q), or circularise them (o), because it is almost impossible and time consuming to draw shapes so percisely by hand. Buildings with metal or pitched roofs tend to have square corners; round buildings are identifiable by the distinctive cresent shaped shadow they cast. Unless the building is clearly a different shape then it's best to assume that it should be rounded or its corners should be squared. In the iD Editor, you can right click for access to editing functions. Since roofs tend to overhang walls trace the initial shape slightly smaller to allow a buffer for any change in size that may occur. In JOSM use the [buildingstools plugin](osm.wiki/JOSM/Plugins/BuildingsTools). In ID you must draw the shape accurately enough else shapes will not completely square. This [video about squaring features in ID](https://youtu.be/Xs5wX592E1o) has more information and a demo.

Please keep this feedback in mind when contributing in future. Thank you for your contribution. If you want to experience the OSM community or to get timely feedback from other mappers; I recommend that you attend a mapathon. You can find events here https://osmcal.org/

You're welcome! Thank you for your resopnse and contributions. Mapping the geometry of highways can be where a lot of the effort of mapping them lies. Generally the geometry of the highways you added was good so I could just retag them as I have here https://osmcha.org/changesets/171897397

See osm.wiki/Highway_Tag_Africa for tagging highways in Africa and osm.wiki/Good_changeset_comments for use of changeset comments.

You can use the shortcut ctrl+shift+m to open the measurement panel in ID and measure the width of a highway by drawing a temporary line perpendicular to it. Anything <1.8 m is most likely a path.

It's great that you're contributing as part of mapathons. I encourage all contributors to attend mapathons if they can, and there were also people contributing to the project at the same time as your mapathon while I was doing live validation and providing feedback, so I

You're welcome, and thank you for your response and explanation of your workflow. I have taken a look at the Japan GSI seamlessphoto layer in this area and think that you made a good decision to use it to obtain footprint shapes; the way the scenes are lit make the roofs more visible than in other sources. Beware that this layer seems to be compriesed of many secenes captured at different angles so buildings not too far from one another may have visible walls on different sides.

Do you know the claimed positional accuracy of that layer? you can check the meta data of a lot of the default soueces here https://livingatlas.arcgis.com/wayback/#active=21485&mapCenter=12.05732%2C25.09106%2C1&mode=explore

I agree that the building shapes are generally correct, just that some could have been mapped slightly smaller and moved to the base of the building.

When mapping with imagery captured at an angle, please position features where they are at ground level. You can map the outline of the roof and then reposition the building to the base of the walls. I recommend you watch this [video about mapping dense urban areas](https://youtu.be/JAPiGntG6fs) and read this [written guide](osm.wiki/Roof_modelling#Typical_errors_in_the_interpretation_of_roof_geometry_from_aerial_images). Most buildings here are not as tall as those in the video but their walls are visible.

It's true that we cannot always know the exact ammount of roof
overhang. In situations like this I think there is a range of accurate building sizes. I tend to aim for ~ 95% of the size of a pitched roof in general when I cannot see a building's walls directly. This allows me to map quite quickly as I don't have to be pixel perfect and allows enough room for other features.

I also like to use multiple imagery layers to aid my interpretation. You may already know these, but I wanted to share a few tips;
1. Lowering the opacity of layer [2] to 50% while aligning it with layer [1] can aid with the process.
2. You can use the shortcut alt+number to toggle the visibility of layers in JOSM.
3. when working with multiple layers via a tasking manager employ a standard message with the sources you use used and paste that into your task comment; many conrtibutors do not use OSMCha, so will likely not know that you used other sources. If you like you can also post your workflow in a project's comments section if you think it'll help others.

You use the buildingstools and extrude working modes, right?

In future I will be more likely to check the sources attributed to changesets, and the JOSM default imagery layers which are only available in certain areas to gain better understanding of the imagery context.

Thank you for your contribution!

Hi, all footprints you mapped here represent buildings in the imagery. They could be more accurate if you genearally mapped them smaller because pitched roofs tend to overhang building walls.

When mapping buildings, please trace the shape accurately. Accurate building footpritns aid population estimates and prevent issues like data overlaps. Zoom in so that you can see the outline of the building and mark the corners carefully. Exclude shadows and yards when tracing the footprint. Keep in mind that you are looking at the [roofs of buildings](roof:shape=*#Roof_shape), but mapping their footprints. Depending on how the scene is lit, pitched roofs may have light and dark sections that belong to one building. Generally pitched roofs overhang the walls of a building, so a footprint slightly smaller than the roof is accurate. You can scale selected features in ID with shift+(-/+), or JOSM with ctrl.+alt+Lclick & drag. Take care to make contributions that others can build upon.

Thank you for your contribution. If you want to experience the OSM community or to get timely feedback from other mappers; I recommend that you attend a mapathon. You can find events here https://osmcal.org/

Hi, every footprints you added here represents a building in the imagery but they could be more accurate and should have been squared.

When mapping buildings, please trace the shape accurately. Accurate building footpritns aid population estimates and prevent issues like data overlaps. Zoom in so that you can see the outline of the building and mark the corners carefully. Exclude shadows and yards when tracing the footprint. Keep in mind that you are looking at the [roofs of buildings](roof:shape=*#Roof_shape), but mapping their footprints. Depending on how the scene is lit, pitched roofs may have light and dark sections that belong to one building. Generally pitched roofs overhang the walls of a building, so a footprint slightly smaller than the roof is accurate. You can scale selected features in ID with shift+(-/+), or JOSM with ctrl.+alt+Lclick & drag. Take care to make contributions that others can build upon.

After tracing and tagging features which are likely square or round, please remember to square their corners (q), or circularise them (o), because it is almost impossible and time consuming to draw shapes so percisely by hand. Buildings with metal or pitched roofs tend to have square corners; round buildings are identifiable by the distinctive cresent shaped shadow they cast. Unless the building is clearly a different shape then it's best to assume that it should be rounded or its corners should be squared. In the iD Editor, you can right click for access to editing functions. Since roofs tend to overhang walls trace the initial shape slightly smaller to allow a buffer for any change in size that may occur. In JOSM use the [buildingstools plugin](osm.wiki/JOSM/Plugins/BuildingsTools). In ID you must draw the shape accurately enough else shapes will not completely square. This [video about squaring features in ID](https://youtu.be/Xs5wX592E1o) has more information and a demo.

Please keep this feedback in mind when contributing in future. Thank you for your contribution. If you want to experience the OSM community or to get timely feedback from other mappers; I recommend that you attend a mapathon. You can find events here https://osmcal.org/

Hi, the NE footprint envelopes multiple buildings.

Please do not connect the corners of buildings to other buildings or features such as highways or residential areas. In the iD Editor, hold down the `Alt` key to prevent your cursor from snapping to existing data and accidentally creating shared(grey) nodes. This [video about connected nodes](https://youtu.be/ltn1VOiq5_0) has more information and a guide.

Please keep this feedback in mind when contributing in future. Thank you for your contribution. If you want to experience the OSM community or to get timely feedback from other mappers; I recommend that you attend a mapathon. You can find events here https://osmcal.org/
---
#REVIEWED_BAD #OSMCHA
Published using OSMCha: https://osmcha.org/changesets/171751393

Hi Anya,

Assuming you were asking if the western most footprint here represents a building my answer is that, yes, it does, and I think that all the footprints you added here represent buildings. It is obscured by vegetation, but there is evidence to support mapping it as a building. I do not know the exact building you are refering to based on your description; you can add fix me tags with custom values to features to make them stand out fixme=*. The best way to point to a specific feature is to provide a link to its history (via the bottom right panel after selecting a feature in OSMCha) like this one. https://pewu.github.io/osm-history/#/way/1428825813 The best way to ensure you recieve feedback regarding your contributions is to make a note of such links and your questions, then ask someone about them during a mapathon.

Sometimes features are obscured by others in imagery e.g. tall buildings, vegetation, shadows, or clouds. Sometimes using another imagery source in these instances can allow you to view the feature of interest directly. Our goal is to map the ground truth accurately, so if the feature is obscured in all available sources, then use what you can see (and other map data) to estimate its shape, size, position and orientation. Think about what space is already occupied by other features e.g. Consider where a tree's trunk meets the ground.

I hope this answers your question. Thanks for your contribution.

All footprints you mapped here represent buildings in imagery. The Western group of buildings is generally more accurate than the Eastern group which is oversized.

When mapping buildings, please trace the shape accurately. Accurate building footpritns aid population estimates and prevent issues like data overlaps. Zoom in so that you can see the outline of the building and mark the corners carefully. Exclude shadows and yards when tracing the footprint. Keep in mind that you are looking at the [roofs of buildings](roof:shape=*#Roof_shape), but mapping their footprints. Depending on how the scene is lit, pitched roofs may have light and dark sections that belong to one building. Generally pitched roofs overhang the walls of a building, so a footprint slightly smaller than the roof is accurate. You can scale selected features in ID with shift+(-/+), or JOSM with ctrl.+alt+Lclick & drag. Take care to make contributions that others can build upon.

Thank you for your contribution. If you want to experience the OSM community or to get timely feedback from other mappers; I recommend that you attend a mapathon. You can find events here https://osmcal.org/

Good job modifying features beyond the scope of the project; when you decide to do this please add custom text stating what you did and why to your changeset comment (when saving). This is useful to other contributors. You correctly alligned highways to the imagery and added highways. The highways you mapped should be tagged as paths becasue they appear too narrow for a car to use and there is no evidence of a car having driven on them. Appropriate modifiecation of residential area to avoid overlaps with footpritns. All footprints valid; just remember to exclude the shadow a building casts from its footprint. Thank you for your contribution. If you want to experience the OSM community or to get timely feedback from other mappers; I recommend that you attend a mapathon. You can find events here https://osmcal.org/
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#REVIEWED_GOOD #OSMCHA
Published using OSMCha: https://osmcha.org/changesets/171751299